Skip to main content

Full text of "Journal of the Society of Motion Picture Engineers"

See other formats


From the collection of the 




"_ 

Prelinger 
v JLJibrary 



San Francisco, California 
2007 



JOURNAL OF THE 
SOCIETY OF 

MOTION PICTURE 

AND 

TELEVISION 

ENGINEERS 




THIS ISSUE IN TWO PARTS 
Part I, December 1952 Journal Part II, Index to Vol. 59 



VOLUME 59 
July December 1952 



SOCIETY OF MOTION PICTURE 
AND TELEVISION ENGINEERS 

40 West 40th St., New York 18 



CONTENTS Journal 

Society of Motion Picture and Television Engineers 

Volume 59 : July December 1952 



Listed below are only the papers and major reports from the six issues. See the 
Volume Index for those items which generally appear on the last few pages of each 
issue: Standards, Society announcements (awards, Board meetings, committee 
reports, conventions, engineering activities, membership, nominations, section 
activities), book reviews, current literature, letters to the Editor, new products and 
obituaries. 



Dual-Purpose Optical Sound Prints 

C. E. BEAGHELL and G. G. GRAHAM 1 

Theory of Parallax Barriers SAM H. KAPLAN 1 1 

New Direct- Vision Stereo-Projection Screen 

VV. WHEELER JENNINGS and PIERRE VANET 22 

Automatic Torque Controller for Torque Motors . . CARL E. KITTLE 28 
Three-Phase Power From Single- Phase Source . . . A. L. HOLCOMB 32 
Continuous Arc Projector Light Meter . . . HARRY P. BRUEGGEMANN 40 
Use of a Rotating-Drum Camera for Recording Impact Loading De- 
formation D. F. MUSTER and E. G. VOLTERRA 44 

The Navy's Training Film Production Program 

W. R. CRONENWETT and W. M. TIMMONS 49 

Nonsilver Photographic Processes THOMAS T. HILL 58 

August 

Optimum Exposure of Sound Tracks on Kodachrome Films .... 

ROBERT C. LOVICK 81 

Densitometry of Silver Sulfide Sound Tracks . . ROBERT C. LOVICK 89 

Modulated Air Blast for Reducing Film Buckle . . . WILLY BORBERG 94 
A Method of Direct-Positive Variable-Density Recording With the 

Light Valve O. L. DUPY 101 

ii Contents: Journal of the SMPTE Vol. 59 



International Auxiliary Language for Motion Pictures . . MARY BRAY 107 
Un commercial phonoregistrator binaural Interlingua Translation 

of First Page of "A Commercial Binaural Recorder" 

ALEXANDER CODE 108 

A Commercial Binaural Recorder OTTO C. BIXLER 109 

Follow-Focus Device and Camera Blimp for 16mm Professional 

Camera .... LEE R. RICHARDSON and WILLIAM N. GAISFORD 118 

Instantaneous Theater Projection Television System 

VICTOR TRAD and RICARDO MUNIZ 125 
Theater Television Progress NATHAN L. HALPERN 140 

September 

SMPTE Engineering Activities FRED T. BOWDITCH 161 

Explosive Argon Flashlamp 

C. H. WINNING and HAROLD E. EDGERTON 178 
Integrating-Type Color Densitometer .... FRANK P. HERRNFELD 184 

Transmission Color in Camera Lenses PHILIP T. SCHARF 191 

Cameo Film Production Technique 

CHARLES F. HOBAN and JAMES A. MOSES 195 

Auditorium Specifically Designed for Technical Meetings 

D. MAX BEARD and A. M. ERICKSON 205 
Safety Requirements in Projection Rooms and Television Studios . . 

SAMUEL R. TODD 212 

Military-Type Lenses for 35mm Motion Picture Cameras 

PAUL C. FOOTE and R. E. MIESSE 219 
October 

Basic Principles of the Three-Dimensional Film 

RAYMOND SPOTTISWOODE, N. L. SPOTTISWOODE and CHARLES SMITH 249 

(for three errata, see Dec. p. 516) 
Drawing in Three Dimensions for Animation and Stereoscopic 

Processes ERNEST F. HISER 287 

Animation for Individual Television Stations . . . ERNEST F. HISER 293 
X-ray Motion Picture Techniques Employed in Medical Diagnosis and 

Research . S. A. WEINBERG, J. S. WATSON, JR., and G. H. RAMSEY 300 

Appendix: A New Kodak //0.75 Fluro Ektar Lens 

W. E. SCHADE 307 
A Precision Color Temperature Meter for Tungsten Illumination . . 

G. H. DAWSON, D. E. GRANT and H. F. OTT 309 

Comparison of Recording Processes (Reprint) . . JOHN G. FRAYNE 313 
A Building-Block Approach to Magnetic Recording Equipment Design 

KURT SINGER and J. L. PETTUS 319 
A-C High-Intensity Arc Slide Projector ARTHUR J. HATCH 335 

Contents: Journal of the SMPTE Vol. 59 iii 



November 

The Economics of High-Speed Photography .... A. C, KELLER 
Transient Pressure Recording With a High-Speed Interferometer 

Camera WILLARD E. BUCK 

Optimum Slit Height in Photographic Sound-Track Reproducers . 

W. K. GRIM WOOD and J. R. HORAK 
Dual Photomagnetic Intermediate Studio Recording 

JOHN G. FRAYNE and JOHN P. LIVADARY 

Television Facilities of the Canadian Broadcasting Corp. . J. E. HAYES 
Use of Ansco Color Film in Commercial Production . REID H. RAY 
A Fast-Acting Exposure Control System for Color Motion Picture 

Prating JOHN G. STREIFFERT 

Motion Picture Studio Lighting Report JOHN W. BOYLE 

Film Dimensions Committee Report E. K. CARVER 

Optics Committee Report RUDOLF KINGSLAKE 

December 

The Electronic Camera in Film-Making 

NORMAN COLLINS and T. C. MACNAMARA 445 

Signal Corps Mobile Television System JOHN S. AULD 462 

Motion Photography for Combustion Research . . F. W. BOWDITCH 472 
Accuracy Limitations on High-Speed Metric Photograph) 

AMY E. GRIFFIN and ELMER E. GREEN 485 
High-Speed Cine-Electrocardiography .... JOSHUA J. FIELDS, 

Louis FIELDS, ELEANOR GERLACH and MYRON PRINZMETAL 493 

Optical Aids for High-Speed Photography 

DAVID C. GILKESON and A. EUGENE TURULA 498 

A High-Speed Rotating-Mirror Frame Camera . . BERLYN BRIXNER 503 
Acoustic Problems at the "Waldbiihne" Open-Air Sound Theater in 

Berlin HANS SIMON 512 

Some Geometrical Conditions for Depth Effect in Motion Pictures 

EUGENE MILLET 517 
Screen Brightness Committee Report . W. W. LOZIER 524 



Contents: Journal of the SMPTE Vol.59 



Dual-Purpose 
Optical Sound Prints 

By C. E. BEACHELL and G. G. GRAHAM 



This paper describes a method of recording and printing two separate sound 
tracks within the normal single-track area for 16mm or 35mm release prints. 
A projector conversion kit for reproducing the double tracks separately or 
simultaneously is also discussed. This technique has possible application in 
reducing distribution costs on foreign versions and in the educational and 
television fields. 



I 



N VIEW OF the greatly increased use 
of films in the fields of government, 
education, television and industry, it is 
often desirable to have available alternate 
sound versions of certain productions in 
order to serve the widest possible 
audience. 

Typical applications of these versions 
are: 

(a) For distribution in foreign coun- 
tries. 

(b) For presentation to audiences of 
different intellectual interests and train- 
ing. For example, a drug firm may 
wish to present one technical version of 
a treatment to a medical audience and, 
using the same visuals, also present a lay 
audience version. 

(c) For television presentation it may 
be necessary to present a film minus 



Presented on April 25, 1952, at the Society's 
Convention at Chicago, 111., by C. E. 
Beachell and G. G. Graham, National 
Film Board of Canada, John St., Ottawa, 
Ontario, Canada. 



the music track because of trade regula- 
tions. 

Because of these and other potential 
needs it is now common practice for 
many film production units to record, 
in addition to the original language 
version of the film, a separate music and 
effects track and a voice and effects 
track. The music and effects track 
may be used for foreign or other English 
language dubbing and the voice and 
effects track may be used for television 
prints where restrictions on the musical 
score are in effect. 

The details of preparing an alternate 
sound version of a completed production 
vary somewhat in different studios, but 
in general they follow this pattern. 

First consideration must be given to 
the economic factors of distribution 
which in turn will indicate the most 
desirable method of presenting the new- 
sound treatment of the film to the public. 
With an eye to the budget, the producer 
and distributor will probably discuss 
these techniques: 



July 1952 Journal of the SMPTE Vol. 59 



(a) The sound volume on the pro- 
jector may be turned down and a com- 
mentary may then be supplied by the 
operator. This method is often used 
in schools with reasonable effectiveness 
but in the hands of an inexperienced 
person the results can be disastrous. 

(b) Subtitles may be added to existing 
prints, which have completed domestic 
distribution, by means of an etching 
process. If additional prints are re- 
quired, subtitles may be printed from 
mattes. Choice of either of these 
methods depends upon the volume of 
prints required. 

(c) For prestige purposes and/or com- 
mercial distribution completely new 
sound tracks may be prepared which 
will permit the film to be presented as a 
standard composite print. Current de- 
velopments in magnetic striping of 
existing and new prints suggests a further 
method of presenting this type of version. 

Perhaps it is in order to discuss 
methods (b) and (c) more fully. 

Etched Subtitles 

In this process, subtitles giving the 
essential text required to explain the 
action of the visuals are added to the 
lower one-third to one-quarter of several 
frames of each scene by means of these 
steps: 

(a) The print embossing plates which 
provide a relief image of the text type 
are made. One European process per- 
mits direct typing on the film and thus 
obviates the need of individual type 
plates. 

(b) The print to be subtitled is 
coated with a bleach-resistant material 
such as paraffin wax. 

(c) At the desired places throughout 
each reel the printing plate is hot- 
pressed on the coated film so that the 
type image penetrates to the emulsion 
surface. 

(d) The film is then run through a 
bleach and clearing bath during which 
the image in the type areas is completely 
removed. 



(e) The wax coating is removed with 
suitable solvent and the subtitles appear 
on the completed print as white letters. 

Matte Printed Subtitles 

In this process a text similar to that 
described above is applied during the 
release printing operations as follows: 

(a) Individual title cards bearing the 
text for each scene are prepared and shot 
on the animation stand. If more than 
one set of mattes is required, black letters 
on a white background may be used to 
provide a printing negative. 

(b) The negative titles are now 
printed on positive stock to provide 
black letters against a clear base. 

(c) The subtitle printing matte is 
synchronized with the release printing 
picture negative and both of these films 
are run through the printer in contact 
with the positive raw stock. The text 
appears as white letters against the 
picture background. 

This is a deliberate simplification of 
the preceding process which involves 
much more consideration of negative 
and positive print densities in the 
subtitle areas than is indicated here. 

Dubbing 

Most of the foreign language dubbing 
is presently done in Europe where con- 
siderable skills in translating and re- 
cording lip-synchronized dialogue have 
been developed over many years. The 
advantages of this arrangement are: 

(a) Translations may be obtained 
which contain the current idioms of 
the area in question and which avoid 
offensive reference to controversial ques- 
tions involving the national, political or 
religious beliefs of the country concerned. 

(b) A relatively large number of 
translators and actors are available who 
have a detailed knowledge of the English 
language and who are trained to inject 
the proper feeling and authenticity into 
the characterizations. 

(c) Most distributing firms have funds 
frozen in various foreign countries and 



July 1952 Journal of the SMPTE Vol. 59 



this fact, coupled with restrictions on the 
import of prints from hard-currency 
areas, makes this method of operation 
desirable from an economic standpoint. 

Recent developments of magnetic 
striping, such as those described at this 
Society's conventions and in the Journal, 
have opened up further possibilities for 
the application of alternate sound tracks 
to existing prints. The high quality of 
reproduction obtained with this system 
along with the simplicity of operation 
should permit its use in the foreign or 
alternate English version field in a most 
practical manner. 

Obviously the application of a foreign 
or alternate English language track to a 
commentary-type film is a reasonably 
simple operation. It becomes quite 
complicated, however, when the sound 
must be supplied as dialogue to match 
the lip synchronism of the visuals. 
Special techniques for analyzing the 
voice portions of the original track and 
selecting words in the new version 
which match the phrasing and inflections 
of the original have been developed by 
De Lane Lee and others in Europe. 
Individual scene loops are recorded on 
magnetic stock in an erase-record cycle 
until a desirable take is secured. The 
individual sequences are later mixed 
with the music and effects track (which 
has been recorded previously) to provide 
the completed track. Usually new tides 
are prepared for release printing versions 
of this type and with these cut into the 
printing dupe and synchronized with 
the sound track the film is ready for 
release printing. Although this latter 
method requires the making of a new 
sound track, it is presently considered 
to be the most effective way of pre- 
senting a supplementary version of a 
film. The methods and techniques to 
be discussed in this paper deal with the 
application and utilization of such 
alternate sound tracks. 

The National Film Board of Canada 
is faced with the continuing problem of 
producing films in both the French and 



English languages for its domestic dis- 
tribution. In addition to this, the 
prospect of increased coverage in Europe 
to assist the Canadian government's 
immigration program as well as greater 
activity in the fields of education and 
television led to study of methods to 
provide greater flexibility in the utiliza- 
tion of 16mm and 35mm prints. 

The use of subtitles was considered 
and abandoned for these reasons: 

(a) It is extremely difficult to present 
sufficient text within the space allotted 
in documentary films where the com- 
mentary is not necessarily linked to the 
visuals in an obvious manner as is the 
case in a story-line type of film. 

(b) The attention of the spectator 
must be divided between the picture 
image and text, and consequently the 
ability to understand the film is reduced. 

(c) In many areas of the world it is 
desirable to show the films to illiterate 
audiences which, of course, reduces the 
effectiveness of this method. 

Magnetic striping provides an ac- 
ceptable quality sound track and is ideal 
in certain circumstances. Its principal 
disadvantages at this time appear to be: 

(a) The cost of new projectors or 
converting existing projectors is quite 
high. This is particularly significant 
in areas where several hundred pro- 
jectors are in use. 

(b) The cost of striping a print and 
transferring the new sound track adds 
considerably to the sale price of the 
print. 

(c) The fact that the sound track 
can be erased and replaced with an 
entirely different track without reference 
to the original producer could have 
serious consequences. By design or 
accident, interpretation of the visuals 
could be used indiscriminately to express 
opinions which would cause embarrass- 
ment to the organization or country 
responsible for production and dis- 
tribution of the film. 

As a result of these conclusions and 
to meet the needs of other agencies of 



Beachell and Graham: Dual-Purpose Optical Prints 




Fig. 1. Close-up of Debrie Sound Adaptor, showing 
sound aperture masks in position. 




Fig. 2. Normal track provided by Maurer Sound Recorder. 
July 1952 Journal of the SMPTE Vol. 59 



government concerned with film dis- 
tribution the following objectives were 
established : 

(a) The overall quality of the sound 
should not be impaired. 

(b) The technique devised must be 
applicable to existing films as well as 
those to be produced in the future. 

(c) In view of the capital investment 
in projectors, any method of changing 
the character of the sound track must be 
accomplished through adaptation of 
available equipment. It was, of course, 
mandatory that any conversion unit 
applied to the projector must not, in 
any way, prohibit its use for projection 
of standard films. 

(d) The technique developed should 
insure an appreciable saving in print 
costs to the distributor and consumer. 

(e) The sound track supplied should 
be that prepared by the producer of the 
film and should remain a permanent 
part of the print itself. 

In view of the success achieved in 
reproduction of the 50-mil optical track 
portion of the striped magnetic sound 
systems, it was decided to concentrate 
on producing a double optical sound 
image each portion of which would be 
50 mils in width. Either of these tracks 
could then be reproduced at will by 
simply inserting a suitable mask in the 
sound scanning beam of a 16mm 
projector. 

In preparing these dual-purpose sound 
prints it was found that two methods 
could be used. With the use of half- 
width masks alternately on opposite 
sides of the sound aperture and a double 
printing operation, the prints may be 
made from existing sound negatives by 
the processing laboratory. To avoid the 
double-printing operation, a similar 
masking technique may be used on an 
optical recorder. In this case two 
separate recordings are made in the 
standard single-track area on an inter- 
lock system by exposing one side, then 
reversing the mask, rewinding the stock 
and exposing the second half. 



Adaptation of Printers 

For the preliminary experimental work 
a double sound head Debrie Matipo 
printer was used. The alternate halves 
of each sound aperture were masked 
with brass shim stock suitably blackened 
to reduce reflection (Fig. 1). The 
Matipo printer is particularly suitable 
for this work since the sound gate is 
slightly undercut from the film path. 
Consequently a mask may be inserted 
in such a manner that it clears the 
moving film by about 0.010 in. 

To adjust the mask a standard nega- 
tive is placed in its normal position on 
the aperture. Over this a piece of 
positive raw stock is placed so that the 
image of the track and the mask im- 
pinges on it when illuminated by the 
printer lamp. With the use of a tool- 
maker's microscope, the mask is moved 
to split the track at the 50-mil position. 
Fine centering of the mask image on the 
positive stock is accomplished by adjust- 
ment of the printer-lamp position. 
Figure 2 shows a section of multiple 
bilateral track from a Maurer recorder. 
The track is split in printing half-way 
between sections 3 and 4. 

Two samples of tracks printed and 
recorded in this manner are shown in 
Figs. 3 and 4. Figure 3 shows the result 
of mask overlap of approximately 0.010 
in. which causes a loss of two tracks. 
Figure 4 illustrates a finer adjustment of 
the masks to eliminate the unexposed 
center strip completely. 

When it was established that the 
unexposed center area could be elimi- 
nated, an alternate use of this technique 
suggested itself. Instead of putting 
entirely different sound tracks on each 
50-mil portion, it might now be possible 
to print or record different portions of 
the same track on each half-track portion. 
To check this reasoning a special mix of 
a sound track was prepared. The 
tracks to be mixed consisted of two 
music, and four voice and effects reels. 
From the dubbers the sound was fed 



Beachell and Graham: Dual-Purpose Optical Prints 




Fig. 3. First track split, show- 
ing effect of mask overlap. 




Fig. 4. Second track split, with masks adjusted to eliminate overlap. 



as shown in Fig. 5. The mixer heard 
the combined effect of all tracks over 
his monitor speakers, but at the record- 
ing stage the signals were bridged so 
that the music was recorded on an inter- 
locked magnetic recorder while the voice 
and effects were picked up on a masked 
optical system. The magnetic track 
was transferred to the opposite half of 



the optical negative and the combined 
tracks were printed onto the positive 
stock. When played on a standard 
projector the full track is reproduced, 
while on an adapted projector the print 
may be played as full sound, voice and 
effects, or music only. This type of 
print appears to offer certain advantages: 
(a) On full-track reproduction, since 



July 1952 Journal of the SMPTE Vol. 59 







fi/VD FILTtfU 


Mtmt 

POTS 

v 


//V OK MIC. 






- 


Y' 

v 






DlfiiOGVB 
f*-Z 




Y? 

v 






FP-J 




Y< 

v 






enters B 




- 
- 

H 


T" 

v 






MVS/C ft 
fP-S 




Y^ 

v 






MUSIC B' 
F.P-6 




Y* 

v 






MUSIC C~ 
FP-7 




Y 7 
V 






re* f* \ 






Fig. 5. Diagram of divided track re-recording system. 



the high- and low-frequency components 
are physically separated, intermodula- 
tion distortion effect in the recording and 
printing stages is greatly reduced. 

(b) The music portion only of the 
track may be reproduced when, for 
example, the print is used for educational 
purposes and the teacher wishes to 
supply his or her own commentary. 
Alternatively, many teachers feel that 
music detracts from the effectiveness of 
an education subject and in such cases 
the voice and effects portion alone may 
be used. 

(c) A third possible application lies 
in the television field. Split-track prints 
may be distributed generally for re- 
production on standard projectors. 
However, the same print may be rented 
or sold to television stations which in 
turn may reproduce only the voice and 
effects portion. This eliminates the 
need for special prints of sound negatives 
where trade regulations prohibit the 



reproduction of film music on television 
networks. 

Mechanical Adaptation of Recorders 

Figure 6 shows plan views of the 
RCA and Western Electric optical 
paths. Suitable half-track masks could 
be installed at the points shown. In 
the Maurer recorder the mask is intro- 
duced at the ultraviolet filter holder 
position so that its image is produced 
sharply on the film in the desired posi- 
tion. During the early experiments 
masks were used at the film plane for 
reasons of convenience. However, the 
points noted in Fig. 6 would permit a 
more precise arrangement for con- 
tinuous use. 

Split-track recording may be used for 
two purposes: 

(a) To divide the contents of a single 
track into two portions: i.e., music, 
and voice and effects; or music and 
effects, and voice. 



Beachell and Graham: Dual-Purpose Optical Prints 







DESIRABLE POSITION FOR 
HALF-TRACK MASK 



Fig. 6. (A) RCA Optical System, plan view; (B) Westrex Optical System, plan view. 



(b) To place within the single-track 
area of a standard 35mm or 16mm 
negative two separate sound versions: 
i.e., English and French tracks, two 
English tracks, etc. 

Where separate language versions are 
required, the originals are recorded 
separately in the regular manner on 
35mm magnetic stock. These tracks 
may then be transferred to the masked 
recorder as described above. 

The particular advantages of double- 
track sound negatives are: 

(a) The laboratory printing step is 
reduced to a standard single operation 
and consequently two print versions 
may be produced for the price of one. 

(b) Any overlap of the masks on the 
sound negative record is reproduced as a 
continuous black unmodulated line on 
the print. This is preferable to the 
white line left by overlapping of the 
masks on the release printer since this 



would raise the noise level when re- 
produced on full-width scanning. 

(c) On a recorder greater accuracy 
of center-line placement can be assured 
and the danger of clipping is reduced. 
In addition, negative recording stock is 
usually in good physical condition so 
that no compensation for shrinkage need 
be applied. 

Projector Conversion 

The prototype model shown here 
(Fig. 7) is a very simple adaptor which 
may be fitted to most 16mm projectors. 
The pivoted mask is U-shaped, with 
adjusting screws for proper horizontal 
positioning of the projector sound 
scanning beam. Since the vertical 
dimension of the scanning beam is 
defined by the optical system of the 
projector, no provision need be made for 
this on the adaptor. This fortunate 
circumstance greatly reduces the manu- 



July 1952 Journal of the SMPTE Vol. 59 



facturing cost of the unit. With this 
adaptor the sound track may be re- 
produced as full-width normal, 50-mil 
left and 50-mil right. The actual width 
of the scanned area is slightly under 50 
mils to avoid picking up unwanted 
signal due to weave in the film path or 
miscentering due to shrinkage. Further 
fine adjustment may be made by means 
of the adjusting screws if necessary. 

The mask is suitably curved so that 
it will not cut into the film in the event 
of a break or when the end is passing 
through. 

Using either half of the split track, 
the sound quality is quite acceptable. 
For experimental purposes an old Bell & 
Howell No. 179 projector (Fig. 8) was 
selected as representative of a type still 



Fig. 7. 16-mm projector adaptor. 




Fig. 8. Adaptor in posi- MS 
tion on Bell & Howell, 
Model 179. 







BeacheU and Graham: Dual-Purpose Optical Prints 



used extensively in Canada. With the 
amplifier in good working condition 
and the sound scanning beam balanced 
to li db across its full width, the 
sound level of the half-track is down 
approximately 5 to 6 db. The fre- 
quency response characteristic remains 
unchanged. Signal-to-noise ratio of the 
projector is not affected since the scan- 
ning beam is mechanically reduced by 
one-half. There is an increase of 
amplifier noise since the gain must be 
increased to compensate for the volume 
loss on the half-track. However, this is 
not serious for all normal requirements. 

While this system is particularly 
adaptable to variable density and 
multiple bilateral area tracks it is also 
applicable to other types of area tracks 
with the exception of unilateral records. 

In conclusion this 50-mil optical track 
system appears to offer the following 
advantages which are applicable to 
either 35mm or 16mm black-and-white 
or color film prints: 

(a) Double- and possibly triple-version 
tracks may be produced on a single 
print at very low cost, thus introducing 
economy for film users in various fields. 

(b) Using the split tracks for inde- 
pendent recording of the low- and high- 
frequency components of a single sound 
track will reduce intermodulation dis- 
tortion. By means of selective playback, 
greater utilization of the same print 
may be made. 

(c) The cost of adapting a projector 



for this purpose will probably be less 
than fifteen dollars per machine and the 
adaptor will not, in any way, limit the 
projector for use with regular films. 

Discussion 

John G. Frayne: I would like to offer a 
suggestion if I may to Mr. Graham. It's 
possible with the valve which I believe 
you showed in that slide, the RA-1238 
push-pull valve, to reconnect it so that 
you can record two independent tracks 
simultaneously. Have you tried that? 

Gerald G. Graham: No, not yet. 

Dr. Frayne: It can be done very easily. 

Mr. Graham: It's an excellent suggestion. 

Dr. Frayne: You merely put the two 
separate signals on the two outside noise- 
reduction ribbons, superimpose the noise- 
reduction currents on these and keep the 
center ribbon as a mask. You thus get 
two independent tracks. In the case of 
variable area, you simply connect each 
ribbon to an independent signal and noise- 
reduction input and thus obtain two 
separate VA tracks. 

Mr. Graham: Yes, to date in the experi- 
mental work we haven't actually been 
delving into the recording system. We've 
tried to work outside of that. That is 
something we would like to do next. 

H. R. Kossman: The speaker mentions 
making superimposed titles. However, 
there is another method it's a Debrie 
printer which accomplishes this by pro- 
jecting one single text frame onto the 
negative while the printer runs. This 
means a considerable saving in matte 
costs. 



10 



July 1952 Journal of the SMPTE Vol. 59 



Theory of Parallax Barriers 



By SAM H. KAPLAN 



The parallax barrier, which is a type of selective masking device now being 
applied in color television and in stereoscopic imagery, is discussed. A brief 
history along with the principle and geometric relationship underlying its 
operation is given. Various systems employing two or more image elements 
per aperture and utilizing the maximum image area are described. It is 
also shown that nonplanar and nonparallel arrangements are possible, and 
that plane barrier surfaces may be coupled to nonplanar image surfaces. 
Furthermore, lenses may replace the mechanical-type barriers resulting in 
a more light-efficient system. Formulae are presented and specific applica- 
tions to multiple-color television tubes are discussed. 



PARALLAX BARRIER may be defined 
as a masking device which, when inter- 
posed between an object space and an 
image space, prevents any given part 
of the image space from being sighted 
from any but a given set of predeter- 
mined directions. Since both light and 
electron beams travel along straight 
paths, the laws of geometric optics 
apply irrespective of direction of travel 
along this path. Consequently, parallax 
barriers can be utilized where a viewing 
screen is observed from predetermined 
directions as in stereoscopic imagery, 
or where a luminescent screen is im- 
pinged upon by electron beams coming 
from specified directions, as in color 
television tubes. Parallax barriers are 
now being used for both of these pur- 
poses. 

Presented on April 21, 1952, at the Society's 
Convention at Chicago, 111., by Sam H. 
Kaplan, Consultant, 3713 W. Arthington, 
Chicago 24, 111. 



Brief History 

The concept of the parallax barrier 
is generally attributed to Berthier 1 of 
France who suggested it in 1896. How- 
ever it was first applied by Frederick E. 
Ives 1 to produce stereoscopic still pictures 
in 1904. These were called "parallax 
stereograms" and required no separate 
viewing accessories. The substitution 
of lenses as an alternate to mechanical 
blocking barriers was proposed by 
Gabriel Lippman of France in 1908. 2 
A barrier system with more than two 
elements behind each barrier aperture 
was invented by C. W. Kanolt who 
obtained U.S. Patent 1,260,682 on 
March 26, 1918. His stereoscopic pic- 
tures were called "parallax panorama- 
grams" and revealed a multitude of 
stereoscopic views as the picture was 
viewed from different angles. A radial 
nonparallel-type barrier system was 
invented by B. T. Ivanof 3 who first 



July 1952 Journal of the SMPTE Vol. 59 



11 




Fig. 1. Two-element barrier. 



used it in 1941 to show projected stereo- 
scopic motion pictures in Russia. 

The use of parallax barriers as ex- 
ternal attachments to cathode-ray tubes 
for stereoscopic television is included in 
several patents. The use of such 
parallax barriers inside a cathode-ray 
tube, as a positive means of insuring 
that portions of a mosaic screen would 
be subjected to bombardment only by 
a predetermined electron beam, was first 
revealed in German Patent 736,575, 
issued June 22, 1943. The application 
date is July 12, 1938, and the inventor 
was Dr. Warner Fleshig of Fernseh A.G. 

Principle and Geometric Relationships 

The application of the parallax 
barrier to stereoscopic pictures can serve 
to illustrate the principle (see Fig. 1). 
Two pictures taken from slightly sepa- 
rated points of view and designated as 
left and right views, are divided into 
fine strips and reassembled on an 
alternate basis: RI, L 2 , R 3 , L 4 , R 5 , 
etc., (the odd numbered L strips and the 
even numbered R strips are not used). 
In front of the reassembled picture 
(labeled "I" plane) there is placed a 
series of opaque strip barriers separated 



by transparent strips of equal width 
(labeled "B" plane). If the barrier is 
properly located between the picture 
and the viewer's eyes (labeled O t and 
O r ), the left eye will see only the strips 
L 2 , L 4 , L 6 , etc., (the R strips being 
hidden by the barriers). Likewise, the 
right eye will see only strips R 1} R 3 , 
R 5 , etc. If the strips are of such small 
width that they are not individually 
resolved by the eye, a stereoscopic picture 
results, since each eye sees only the pic- 
ture corresponding to its field of view. 

From simple geometrical considera- 
tions it is possible to determine that the 
relationship between image distance 
(D), distance between image strip cen- 
ters (I), separation of eyes (O), and 
distance of eye plane to image plane 
(C), is: 



1C 



+ 1 



(1) 



Although the distance between the eyes 
(labeled as "O" points) and the image 
increases steadily in going from the 
center to the edges of the image, the 
bandwidth of the picture strips and 
barrier strips is constant and is inde- 
pendent of the angle between any image 



12 



July 1952 Journal of the SMPTE Vol. 59 



R 3 




Fig. 2. Two-element barrier showing repeating "O" points. 




Fig. 3. Alternate viewing of same element by different "O" points. 



portion and the line of viewing. Proof 
is given in an article by C. S. Szegho. 4 
The width (B') separating the barrier 
strips can be determined from similar 
triangles to be: 



(2) 



In this case the distance B between 
barrier strip centers is 2B'. 

The question arises whether there are 
other points in addition to Oi and O r 
from which the same picture (i.e., left 
image seen by left eye and right image 



seen by right eye) can be viewed. As 
shown in Fig. 2, by projecting rays from 
the image through the apertures be- 
tween barriers, using in turn different 
barrier spaces for a given image strip, 
one can obtain an alternating sequence 
of equally spaced Oi and O r points. 
Any combination of d and O r points, 
whether adjacent or nonadjacent, will 
fulfill the condition that one "O" point 
"sees" only one image set and the 
second "O" point sees the alternate 
image set. Figure 3 shows in more 
detail the relationship between these 



Sam H. Kaplan: Theory of Parallax Barriers 



13 




Fig. 4. Three-element barrier system; 
second- and third-order barrier planes shown. 




Fig. 5. One cycle of a six-element system. 




Fig. 6. Reciprocal relation 
between "O" and "I" planes; 



1+6 



14 



July 1952 Journal of the SMPTE Vol. 59 



different "O" points and a given image 
strip. The only difference is that a 
particular strip (in this case LI) is 
"seen" by (Oi)i, by (Oi) 2 , and by 
(Oi) 3 through different barrier plane 
apertures. 

Barriers for More Than Two 
Image Elements per Aperture 

Instead of two viewing points (called 
"O" points) coupled to two mutually 
intermeshed image area sets, three or 
more intermeshed image area sets can 
be coupled to a corresponding number 
of viewing points. Such an arrangement 
is possible if the barrier has a ratio of 
aperture area to total barrier plane 
of 1/JV or less, where JV equals the 
number of points coupled to a similar 
number of sets of mutually exclusive area 
elements. For a three-element arrange- 
ment the width of the barrier member 
must be at least twice that of the aper- 
ture width; for a four-element arrange- 
ment the barrier width is at least three 
times the aperture width. A three- 
element arrangement is shown in Fig. 4. 
One section of a six-element arrange- 
ment is shown in Fig. 5. 

While the "O" plane has been con- 
sidered up to this point as a viewing 
plane, the various "O" points in the 
"O" plane may also be considered as 
origins of electrons or other radiation, 
for the purpose of creating a parallax 
system consisting of an image plane, a 
barrier plane and an origin (or object) 
plane. 

In order to generalize the theory of 
parallax barriers, consider the barrier 
plane to be covered with a regular re- 
peating dot pattern (such as the rec- 
tangular dot pattern shown in Fig. 6). 
If there is a point source of rays in the 
O plane, the pattern in the barrier 
plane will be projected on the image 
plane I and will be enlarged in the 

ratio of I _ Y If any particular 

point in the above projected image 
plane I is considered as an origin, then 



it will project the barrier plane pattern 
onto the O plane and the pattern will 
be enlarged in the ratio of G/D. Any 
dot in the resulting O plane pattern 
can be shown to be in the correct 
position for projection of the barrier 
pattern onto the previously projected I 
plane pattern. The different dots in 
the O plane can be considered to corre- 
spond to the (OOi, (Oi) 2 , (Oi) 3 points 
of Fig. 3. Thus we see that the patterns 
of image and origin planes bear re- 
ciprocal relationship to each other, 
and the functions of O and I may be 
interchanged. Mathematically: 



1 = - + 
B O T 



(3) 



where B, O and I are the pattern sizes 
in the B, O and I planes, respectively. 
The dots of these patterns serve as the 
centers for the area patterns actually 
used. Desirable area shapes and pat- 
tern arrangements are discussed below. 
To develop a two-element, a three- 
element or an jV-element arrangement, 
it is necessary to intermesh two, three 
or JV patterns in both the image and 
origin planes between each other. 
Each image pattern is then coupled to a 
corresponding mutually exclusive origin 
pattern. Figure 7 illustrates a two- and 
three-element arrangement. 

Arrangements of Image Elements 

Practical considerations call for the 
maximum utilization of available area 
in the image plane. Although many 
geometrical patterns exist which can 
cover an entire area, only a few meet 
the two following criteria: 

(1) The patterns must contain only 
the same shape and size elements. 

(2) All the elements must have the 
same orientation. 

Arrangements meeting these criteria 
are parallelograms (including rectangles 
and squares) and hexagons. Although 
an area may be covered by isosceles 
triangles, such an arrangement does 
not fulfill the second criterion since 



Sam H. Kaplan: Theory of Parallax Barriers 



15 



Fig. 7a. Two intermeshed patterns. 



Fig. 7b. Three intermeshed pat- 
terns; circle area elements also 
shown. 



Fig. 8a. Rectangular three-element 
pattern. 




Fig. 8b. Hexagonal three-element 
pattern. 




$ 

a l 3 '/ 








2 - 

X l|3 



2.1 3 






--- 

2-1 3 X 

"" x 

1 



Fig. 9a. Open barrier arrangements, Fig. 9b. Open barrier arrangements, 

staggered. nonstazerered f bands). 



I 2 3 



2. 3 \ 



b. Triangular 




Fig. 10. Preferred three-element origin 
arrangements. 

half the triangles have one orientation 
and half are oriented 180 out of phase 
with the first set. From a practical 
point of view, ellipses (including circles) 
may be considered to fulfill the necessary 
conditions, although only 90.7% of the 
available area is covered when these 
are in the close-packed arrangement 
shown in Fig. 7b. 



nonstaggered (bands). 

Classification of Barriers 

Closed- and Open-Barrier Structures. It 
is possible to classify parallax barriers 
with respect to aperture boundaries. 
The apertures can either meet or not, 
and the barriers can then be called 
"open" or "closed," respectively. In 
the closed-structure type, each aperture 
is completely surrounded by barrier. 
Open-barrier structures consist of bands, 
either straight or staggered. 

Three-element arrangements can 
utilize either open- or closed-type bar- 
riers. In order to transform open 
barriers to the closed-barrier type, 
alternate image row areas must be 
staggered 180 with reference to the 
preceding row. Figure 8 illustrates the 
image plane arrangement for rectangles 
and hexagons to go with a closed-type 
barrier. See Fig. 7b for a similar ar- 
rangement for circles. Where rec- 



16 



July 1952 Journal of the SMPTE Vol. 59 



tangles are used and the elements are 
under one another, only an open-barrier 
band-type arrangement is possible 
(shown in Fig. 9). 

In the three-element arrangement one 
origin point is usually selected from 
each of the three intermeshed O plane 
patterns. For most purposes it is 
desirable to choose the O points as close 
together as possible. The three points 
may be selected from three adjacent O 
points in a single line, leading to a 
"collinear" arrangement shown in Fig. 
lOa, or the O points may be selected to 
constitute the apices of a triangle a 
"delta" arrangement leading to an 
even closer pattern, as shown in Fig. lOb. 

Higher Order Barriers. The barriers 
already described have a reciprocal 
arrangement between image, source and 
barrier pattern centers. By looking 
again at Fig. 4, one may see that there 
are other possible barrier locations 
(formed by ray intersections) which 
fulfill the basic condition of having each 
image area "seen" by only one of the 
O points. These locations are shown on 
the drawing as B 2 , B 3 , etc. and corre- 
spond to the selection of nonadjacent 
O points from a smaller submultiple O 
plane pattern. The first barrier plane 
shown has the O points taken from 
adjacent points of a pattern having a 
separation of distance O. The second 
barrier plane corresponds to the selection 
of alternate points of a pattern having 
points separated by distance O. The 
third plane corresponds to the selection 
of every third point of a pattern with 
point separation of %O. This third 
barrier plane cannot be used in a three- 
element arrangement since it means 
all three O points have been taken from 
the same point set in the O plane, 
instead of having one O point taken 
from each of the three intermeshed sets. 
Each O point would "see" the same 
image set, and the other two image area 
sets would be seen by none of the O 
points. The formula for these other 



image-to-barrier-plane spacings is given 
as: 



D 



/TIC 
+ Kl 



(4) 



where K is the ratio of O distance to the 
smallest O pattern spacing. When using 
these higher order barriers, the elements 
of a given image cluster are "seen" by 
the O points through different apertures, 
instead of through a single aperture as 
is the case for the first barrier plane. 

Nonplanar Barriers and Images. The 
parallax barrier principle is not limited 
to three parallel planes. Consider a 
spherical surface I and two O points, 
as shown in Fig. 11 a. The locus of the 
intersections of pairs of rays which are 
a fixed distance apart on the image 
surface and pass through the two given 

points will sweep out a curve which 
meets the parallax criteria. This sur- 
face will not be a sphere. In this case 
the size of the elements on the image 
surface is uniform. By sacrificing this 
condition, any given barrier B and image 

1 surfaces can be arbitrarily chosen to 
meet the parallax condition for any 
given O points. For example, in Fig. 
lib, curve I can be a circle (in three 
dimensions spherical) and curve B may 
be a plane or a sphere with any given 
radius. The patterns on I and B must 
be constructed by a point-by-point 
method. An example of a two-element 
construction is illustrated in Fig. lla. 
Starting with line 1 connecting O 2 and 
Ii, draw line 2 connecting d and B 3 
(the point of intersection of line 1 and 
curve B), continuing on to curve I. 
Line 3 then connects O 2 and I 2 (the 
point of intersection of line 2 and I). 
Line 4 connects Oi and B 2 (the point of 
intersection of line 3 with B), etc. In 
other words, O 2 lines connect with 
previous intersection points on I and 
Oi lines connect with previous inter- 
section points on B. The examples are 
shown in two dimensions. The three- 



Sam H. Kaplan: 



of Parallax Barriers 



17 




Fig. lla. Construction of spherical "I" and "B" surfaces, nonuniform elements. 



"0" 



2 




Fig. lib. Spherical "I" and plane "B surfaces. 



dimension arrangement necessary for 
any practical use is more complicated. 

The above analysis is based upon a 
100% utilization of available image 
area. It may be desirable to have both 
fixed surfaces of given shapes and a 
uniform pattern on one of the surfaces. 
This can be done, but only by sacrificing 
some of the image area. For example, 
the surface I can be chosen as spherical, 
and the barrier surface as a plane with 
a uniform dot pattern. This can be 
done if the aperture size in the plane 
barrier is small enough to avoid over- 
lapping patterns on surface I. 

The Radial-Type Barrier. If the image, 
barrier and source surfaces are planar, 
they need not be parallel. The above 
principles can be used to generate 
nonparallel arrangements. One such 
arrangement of interest is the radial 



plane arrangement, invented by Ivanof 
and used for stereoscopic pictures. As 
shown in Fig. 12, all three planes meet 
in a common line of intersection and all 
band patterns of I, B and O planes 
converge toward a single point on 
this common line of intersection. For 
motion pictures the I plane comprises 
the screen; the B plane, the parallax 
barrier; and the audience, the O plane. 
This arrangement permits a large 
number of seats to satisfy the parallax 
condition, in contrast to the parallel 
plane arrangement where only one row 
in the theater can meet the necessary 
condition. Of course, if the rows could 
be stacked vertically instead of hori- 
zontally then the parallel plane arrange- 
ment would be suitable. 

The Venetian-Blind Barrier. Instead of 
a separate barrier plane, the surface 
itself can be shaped to provide the 



18 



July 1952 Journal of the SMPTE Vol. 59 




Fig. 12. The radial barrier arrangement. 




Fig. 13. Venetian-blind barrier. 



necessary parallax condition as shown 
in Fig. 13. The sides of the slats form 
two of the three image areas. The 
surface now resembles a Venetian blind. 
The height of the slats is equal to the 
distance D as in the other arrangements 
and is determined by the construction 
methods and formulae already given. 

Physical Limitations 

and How to Minimize Them 

Light Loss Caused by the Barrier. One 
defect in the practical application of 



parallax barriers is the transmission 
loss introduced by the barrier itself. 
This limitation can be minimized by 
replacing each aperture or slit by a 
spherical or a cylindrical lens, as shown 
in Fig. 14. Replacing the aperture by 
a larger size lens can theoretically cut 
the barrier loss to zero. Instead of acting 
as a mechanical barrier, the lenses 
refract or converge the rays to the proper 
position on the image surface. In 
stereoscopic picture processes modern 
practice calls for cylindrical lens elements 



Sam H. Kaplan: Theory of Parallax Barriers 



19 



2 




Fig. 14. Lens equivalent of barrier; finite "O" points shown. 




Fig. 15. Effect of finite size of "O" to avoid overlapping; 
"I" must be reduced to "I"', or "B"' must be reduced to "B' 



molded into the film base. If one deals 
with electron rays instead of light, elec- 
tron lenses can be used, and the apertures 
themselves can act as the electron lenses. 
Owing to the focusing action, these 
apertures, serving as electron lenses, 
can be larger, thus increasing the num- 
ber of electrons reaching the image 
plane I. To make the apertures behave 
as electron lenses, it is only necessary to 
provide for an electric field between I 
and B greater than between B and O. 

Finite-Area Sources. All previous dis- 
cussion has been on the basis of point 
sources in the O plane. Actually, 
especially in electronic apparatus, the 
O points have appreciable area. In 
order to ensure that each O point sees 
only its own image plane patterns when 
using barriers (rather than lenses), it 
is necessary (see Fig. 15) to reduce 
either the size of the barrier plane 
apertures B' or the size of the image 
plane elements I', in either case main- 
taining the same separation distance 
between apertures and image elements. 
Figure 15 shows the proper geometrical 



solution to achieve the nonoverlapping 
condition of image areas. The reduced 
sizes are by similar triangles: 



(6) 



where O' is size of O area and B' and 
I' are the sizes of apertures and image 
elements, respectively. The reduced 
B* or I ' size will result in loss of efficiency 
by reducing the number of rays from the 
O points which can be utilized. 

Practical Application of 
Barriers in Cathode-Ray Tubes 

The parallax barrier is particularly 
suitable as an internal member in 
cathode-ray tubes, permitting positive 
screen area control and ensuring that a 
given beam impinge only on a given 
portion of the fluorescent screen. Speci- 
fied screen areas are associated with a 
desired source of electrons, and electrons 
from other sources are blocked from the 



20 



July 1952 Journal of the SMPTE Vol.59 



same area by the barrier. The control 
is effected by the real or apparent 
position of the electron source. Either 
a separate electron gun is used for each 
independent set of elements or the beam 
originating in a single electron gun may 
be successively shifted through the proper 
O points. Such cathode-ray tubes can 
be used in multitrace oscilloscopes 
giving each trace a different color, or as 
multicolor radarscope for differentiating 
by color such things as moving targets, 
radar beacons, etc. The most important 
application, however, appears to be for 
color television in two-, three- or four- 
color sequential or simultaneous-type 
systems. A large number of tricolor 
picture tubes are being built on this 
principle. 4 ' 5 - 6 At present the applica- 
tion of the parallax barrier principle in 
a cathode-ray tube represents the most 
promising solution for an all-electronic 
color television viewing device. 



Acknowledgments 

The author wishes to acknowledge 
the advice and assistance of Dr. G. S. 
Szegho and co-workers of the Rauland 
Corp., Chicago, 111., in the preparation 
of this paper. 

References 

1 . Josef Maria Eder, History of Photograph}!, 
Columbia University Press, New York, 
1945, p. 383. 

2. Ibid, p. 669. 

3. Denis Segaller, "The Russian stereo- 
scopic cinema," Discovery, 355-358, 
361, Nov. 1949. 

4. C. S. Szegho, "Experimental tri-color 
cathode-ray tube," Tele-Tech, 9: 34-35, 
July 1950. 

5. H. B. Law, "A three gun shadow mask 
color kinescope," Proc. IRE, 39: 1186- 
1194, Oct., 1951. 

6. R. R. Law, "A one-gun shadow mask 
color kinescope," Proc. IRE, 39; 1194- 
1201, Oct. 1951. 



Sam H. Kaplan: Theory of Parallax Barriers 



21 



New Direct- Vision 
Stereo-Projection Screen 

By W. WHEELER JENNINGS and PIERRE VANET 



This paper discusses the development of a new direct-vision stereo-projection 
screen. It permits the audience to see three-dimensional color motion pic- 
tures and slides without the aid of conventional polarized viewing glasses. 



J? OR MORE THAN half a century, 
thousands of dollars have been invested 
by researchers in the hope of developing 
a good commercial free-vision stereo- 
projection screen. The problems en- 
countered have been very complex. 

First, let us re-examine the mechanism 
of our visual impressions. We see 
objects in relief because of the perception 
of each of our eyes of a point located in 
space and observed at different angles 
that correspond to the distance between 
the eyes (Fig. 1). The convergent 
action of our eyes enables us to estimate 
by exploration the various distances of 
different points located in space. 

The image received on the retina of 
the right eye is not the same as received 
by the left eye. In order to get the 
impression of relief, it is necessary to 
project two views taken at different 
angles and to avail oneself of means 
that will enable each eye to see only the 



Presented on April 22, 1952, at the Society's 
Convention at Chicago, 111., by W. 
Wheeler Jennings, 7549 South Clyde 
Ave., Chicago 49, 111., and Pierre Vanet, 
Societe des Anciens Etablissements, A. 
Mattey, Paris, France. 



picture it should receive at the exclusion 
of the other. 1 

In order to get natural binocular 
vision under our existing stereo-projec- 
tion processes, it is necessary for the 
spectator to wear special polarized or 
red and green viewing spectacles. 

We will deal here only with the 
processes of stereo projection that give 
us directly and collectively three-dimen- 
sional screen images as seen with our 
natural vision. 

The Noaillon Theory 

In 1928, Professor Noaillon, of Brus- 
sels, Belgium, developed a selector sys- 
tem, made up of radial converging lines 
in the form of grills with very wide 
openings. This system consists of three 
reclining grills shaking or oscillating in 
their own plane around their meeting 
points, as shown in Fig. 2. 

Figure 3 shows projection on screen 
E through this radial-lined network 
which determines the selective vision 
surfaces. Starting from the stereo-pro- 
jector G and D, representing the left 
and right stereo images, the projected 
image travels to the meeting point O 



22 



July 1952 Journal of the SMPTE Vol. 59 



TsTzT, 




Figure 1, 



Figure 2. 




Gz 




\V\\\M mi'' 'it. 

FSSff 




Figure 3. 



(7 

Figure 4. 



of all the lines T of the converging 
grills. Direct-vision zones G2, D2, Gl 
and Dl radiate on surface P. The 
convergent setting of the selector grills 
brought an important improvement in 
the projected stereoscopic vision of 
depth. 2 

The Findings of Russia's Ivanov 

In 1945 and 1946, we had newspaper 
reports of excellent 35mm stereo motion 
pictures and free-vision theater projec- 
tion in Moscow. Much of the informa- 
tion sounded far-fetched, especially con- 
cerning the technical means employed. 

Since that date, a translation from 
the Russian reveals most of the steps 
used in their process: The screen em- 
ployed was of lined network design 
converging, similar to the Noaillon 
theory shown in Fig. 2 and 3, but 
Ivanov's network is stationary. This 



weblike network shown in Fig. 4 con- 
sists of more than 30,000 white enameled 
wires stretched from the top of the 
screen T to the meeting point on the 
bottom O. The shaded portion is the 
projected picture area. These wires 
pull a total tension of 30 tons. The 
total weight of the screen is approxi- 
mately 6 tons. Figure 5 is a schematic 
of Russian origin showing the vertical 
screen format of the split frame. The 
stereo-screen image is estimated to be 
approximately 12 ft X 9 ft. Because 
of the very narrow and limited vision 
zones, the theater in which this screen 
is installed seats only 250 people. 

According to Ivanov, the theory of 
Noaillon brought out the following 
defects: (1) considerable absorption 
of light and (2) a very narrow observa- 
tion zone, which does not allow the 
spectator to move his head. These are 



Jennings and Vanet: Direct- Vision Stereo Screen 



23 



-9000 




G 
Figure 6. 

all faults common to methods using 
the fixed stretched network screen. 

In an attempt to remedy these faults, 
the Russians sought to achieve a se- 
lector system consisting of conical con- 
verging diopters. Unable to achieve 
the diopters mechanically by means 
used in optics, they tried to obtain the 
results by photographic means, probably 
by utilizing the properties of bichromate 
on the film emulsion, which permits an 
apparent relief. 

Nevertheless, the Russians have made 
a careful study of the momentous prob- 
lems of stereoscopic motion pictures, but 
they have struck a technical impossi- 
bility in realizing a suitable selector of 
transmission that does not produce the 
faults of light absorption and diffraction 
already discussed. 



We have discussed the principal 
obstacles stopping the use of lined 
networks so that you will know of the 
difficulties of direct-vision stereoscopic 
projection. 

Noaillon proposed to solve the prob- 
lems by utilizing oscillating grills starting 
with a selector system with much larger 
openings between grills, which simplifies 
the construction of the stereoscopic 
network. 

A New Direct- Vision 
Stereo-Projection Screen 

Francois Savoye, member of the 
Commission of Color and Relief of the 
French National Cinema Centre, solved 
some of these problems in the design of 
this new free-vision screen. 

This system is based on the properties 
of stereo-selection given by a rotating 
conical shaped grill T as shown in 
Figs. 6 and 8, moving around the 
surface of the screen E. This is part 
of the Noaillon theory with formation 
of converging zones, on the plane 
perpendicular to the plane on the screen. 
This device enables the collective direct- 
vision of stereoscopic pairs. 3 The im- 
pressions of relief are obtained in the 
same manner as by natural vision. 
Each spectator sees the right picture D 
for the right eye and the left picture G 
for the left eye. The rotating grill 
driven by motor M produces total 
shading, by persistence of vision sweeping 
the screen, thus showing the whole 
picture with all its detail in color or 
black-and-white. 

Figure 7 shows a 5-ft screen with a 
projected stereo-image. This was photo- 
graphed with a stereo-camera from the 
spectator's seat. 

For the sake of simplicity, we will 
describe the engineer's model. The 
revolving grill in Fig. 8 is constructed 
of 108 aluminum bars forming the conical 
section. The top support of the cone 
is 36 in. in diameter. This accommo- 
dates a beaded screen 18 in. X 24 in. 
Each bar is set on geometric lines at 



24 



July 1952 Journal of the SMPTE VoL 59 







Figure 7. 




Figure 8. 
Jennings and Vanet: Direct- Vision Stereo Screen 



25 



an angle of 20 to the screen. The 
spacing must be accurate and the ratio 
between the opening and the width of 
the bar is 3 to 5 at the top and 2 to 5 
at the bottom. 

The path of the selector grill is so 
designed as to have zones of vision 
every four degrees as shown in the seat- 
ing arrangement in Fig. 9. The correct 
viewing distance is 2\ to 6 times the 
width of the screen. It is simple to 




Figure 9. 



pre-set the seats in the vision zone of 
40. Rl, R2, R3, R4 and R5 repre- 
sent the rows of seats. G and D repre- 
sent the vision zones. OG and OD 
represent the two images of the stereo- 
projector. The spectator will naturally 
keep himself in a suitable vision zone 
that is not rigid, so he may move his 
head slowly until the visual accommoda- 
tions are most favorable. 

The direction of rotation of the se- 
lector grill is from left to right, turning 
at a constant speed of four turns a sec- 
ond. When projecting motion pictures 
it was found necessary to use a syn- 
chronous motor to turn the grill, to 
eliminate any stroboscopic interference 
with the projector's shutter. 

The overall light-loss in projection on 
the large screen shown in Fig. 7 is 
estimated to be in the neighborhood of 
50%. 

This screen can be fabricated in most 
sizes up to a 10-ft grill. We under- 
stand, Mr. Savoye is now engineering 




26 



Figure 10. 
July 1952 Journal of the SMPTE Vol. 59 



a theater-size screen for an auditorium 
seating 500. 

The projector must be located behind 
the spectator as illustrated in the upper 
half of Fig. 10. When projecting a 
very short distance, the screen should 
be tilted forward about 5. The lower 
half of Fig. 10 illustrates the projection 
of stereo-pairs from a single film by the 
use of beam-splitter P mounted on the 
front of the projector lens. The vision 
zones Zl, Z2 and Z3 are the same as 
shown in Fig. 9. 

We will not attempt to discuss the 
various types of beam-splitters and 
lenses used in taking and projecting 
16mm and 35mm motion picture stereo- 
pairs. This is a specialized technical 



subject that requires individual treat- 
ment. 

There is a great interest in color 
stereo motion pictures. They have a 
definite application in the fields of 
education, industry and science. Every- 
where three-dimensional color motion 
pictures have been exhibited, they have 
had a tremendous audience appeal. 

References 

1. Pierre Vanet "La prise de vue et la 
projection en relief en vision collective 
directe," Rev. photographie optique: p. 
59, Mar. 1951. 

2. Francois Savoye, "Vision direct," Rev. 
photographie optique: p. 34, Dec. 1950. 

3. Francois Savoye, "Les precedes de 
cinema en relief," Rev. photographie. 
optique: p. 23, Feb. 1951. 



Jennings and Vanet: Direct- Vision Stereo Screen 



27 



Automatic Torque Controller 
for Torque Motors 



By CARL E. HITTLE 



The use of the automatic torque controller permits the full advantages of 
torque motors to be realized for film take-up and holdback duty without being 
handicapped by their inherent limitations when operated in the conventional 



THE FIRST sound-on-film re- 
cording and reproducing units were 
made, many types of film-spool drives 
have been used on such apparatus. 
During the intervening years, film-spool 
drives ranging from the slipping belt to 
friction clutch, and, more recently, to 
torque-motor types have been used. 
When torque motors became available 
it was believed that they would provide 
the ultimate in performance, possessing 
more advantages than the previous types 
of drives and none of the disadvantages. 
Experience with these motors taught us 
that in the latter respect this was not 
true. As with the belt and the friction 
clutch drives, we found that torque- 
motor drives may also adversely affect 
the steadiness of film motion in the 
apparatus. Since the characteristics of 



Presented on April 22, 1952, at the So- 
ciety's Convention at Chicago, 111., by 
Edward P. Ancona, Jr., for the author, 
Carl E. Hittle, Radio Corporation of 
America, RCA Victor Div., Engineering 
Products Dept., 1560 N. Vine St., Holly- 
wood 28, Calif. 



torque-motor drives in connection with 
their use for take-up and feed spools in 
film-pulling mechanisms have been 
presented previously before the Society 
in a paper by A. L. Holcomb, * only the 
manner in which they may affect film 
motion will be reiterated. As stated 
in Mr. Holcomb's paper, these adverse 
effects may result from the following: 

1. Sprocket-hole flutter (96 cycle/sec) 
due to high film tension at beginning or 
end of a reel. 

2. Erratic shifting of the film with 
respect to the sprockets at "crossover" 
where the net tension on the film 
reverses. 

3. Gear train chatter due to unloading 
the sprocket gears at crossover. 

All of these contributing factors may 
be eliminated by maintaining constant 
film tension throughout the roll be- 
tween each film spool and film sprocket 
with a differential in tension between 



* A. L. Holcomb, "Film-spool drive with 
torque motor," Jour. SMPTE, 58: 28-35, 
Jan. 1952. 



28 



July 1952 Journal of the SMPTE Vol. 59 



the take-up side and the drag side, 
tension on the latter side being of lesser 
numerical value. Film tension may be 
controlled and maintained within satis- 
factory operating limits by means of the 



automatic torque controller for torque 
motors to be described herein. It is 
equally useful whether .the motor is 
used as a take-up or drag device. The 
principle of operation of the controller 




Fig.. 1. Torque Controller front view. 




Fig. 2. Torque Controller rear view. 
Carl . Hittle: Automatic Torque Controller 



29 



is based on the fact that the torque 
produced by the motor may be varied 
by changing the voltage to the motor. 

Principal elements of the controller 
consist of the following: a film roll 
follower mounted on a rotatable arm, 
a multistep rotary switch actuated by 
the rotatable arm, a set of resistors 
having as many adjustable contact 
bands as there are steps on the rotary 
switch, a solenoid, a relay, and inter- 
connecting wiring. 

The film roll follower arm assembly is 
mounted on the front side of the reel 
panel as shown in Fig. 1. The re- 
mainder of the mechanism is mounted 
on the back side of the panel together 
with the torque motor. 

When used in conjunction with the 
motor serving to drive the take-up spool 
or reel, the device functions in the 
following manner. Sufficient resistance 
is introduced in series with the motor 
at the start of the roll during take-up 
to reduce the film tension to the desired 
value. Thus the usual initial high 
film tension is eliminated at the begin- 
ning, thus removing this cause of 
sprocket-hole flutter. The torque con- 
troller functions in a manner to main- 
tain film tension relatively constant. As 
the diameter of the roll of film being 
wound on the take-up spool increases, 
the roller on the follower arm is moved 
farther from the center of the spool, 
causing the shaft to which the arm is 
attached to be rotated. The rotary 
switch contactor arm, mounted on the 
opposite end of the shaft, is moved 
gradually across the step contacts of 
the switch shown in Fig. 2. Sufficient 
free movement has been provided in the 
mechanical assembly to prevent rota- 
tional eccentricity of the roll of film 
from causing oscillation of the contact 
brush across adjacent switch steps. 
The gradual operation of the rotary 
switch causes small incremental de- 
creases of resistance in the motor circuit 
resulting in a gradual increase in motor 
voltage. This, in turn, due to the 



electrical characteristics of the torque 
motor produces an increase in motor 
torque. 

As applied herein, torque may be 
defined as the product of a force multi- 
plied by a moment arm. In terms with 
which we are concerned, film tension 
and radius of the roll of film are the 
force and moment arm members, re- 
spectively, of the torque equation. 

With proper adjustment of the posi- 
tions of the resistor contact bands, the 
torque may be controlled so as to main- 
tain the film tension constant within 
approximately 2 oz. Based on a normal 
tension of 11 oz, the 2-oz variation is 
less than 20% deviation. Should one 
attempt to use 2000-ft rolls with standard 
2-in. film cores on apparatus equipped 
with friction clutch or standard torque- 
motor take-up drives, the deviation 
would be on the order of 600%. This 
deviation in tension would be nearly 
400% for 1000-ft rolls under the same 
conditions. 

The drag or holdback torque motor 
functions in the inverse manner from 
that for take-up. To prevent free- 
wheeling of the roll of film with the 
motor power off, a friction clutch is 
incorporated in the mechanical as- 
sembly of the motor and reel shaft. 
Since this available friction is sufficient 
to provide holdback as the diameter of 
the roll of film approaches the core, 
motor power is turned off when the roll 
is reduced to a predetermined diameter. 
This is accomplished by means of a 
relay, shown in Fig. 3, which is energized 
from the main motor switch that controls 
the direction of film travel through the 
apparatus. When the relay is energized, 
the electrical connections between the 
last two steps of the rotary switch and 
their associated resistor contact bands 
are opened. Then, when the rotary 
switch arm contacts either of these 
two steps, the electrical circuit to the 
motor is opened. Also, when energized, 
the relay causes additional resistance to 
be imposed in the electrical circuit to 



30 



July 1952 Journal of the SMPTE Vol.59 



R-l 




Fig. 3. Schematic diagram of Torque Controller. 



obtain the decreased torque required 
when the motor is used for holdback. 
Operation of the device in the above 
manner serves to maintain a lower value 
of film tension for holdback operation 
than for take-up with no change re- 
quired in the settings of the resistor 
contact bands for change-over from 
take-up to holdback duty. 

Maintenance of holdback tension in 
proper relation to the take-up tension 
results in the elimination of: (1) re- 
versal of the net film tension and its 
resultant shifting of the film on the 
sprocket plus gear train chatter, (2) high 
film tension at the end of the reel which 
otherwise would tend to produce sprocket- 
hole flutter. 

An automatic follower arm lift has 
been provided to facilitate placement of 



a reel or spool of film on the reel spindle 
or removal therefrom. Lifting of the 
arm to its extreme rotational position 
from the spindle is accomplished by 
means of the solenoid, shown in Fig. 3, 
which is energized when the main motor 
power switch is in its OFF position. 

The automatic torque controller as 
illustrated is suitable for use on mag- 
netic recorder-reproducers or photo- 
graphic reproducers having film handling 
capacity on either reels or spools up to 
2000 ft. Its use is particularly advan- 
tageous in eliminating the extremely 
high film tension which results when 
2000-ft rolls wound on standard film 
cores are used. Obviously the same 
principle may be applied for reels of 
larger diameter. 



Carl . Hittle: Automatic Torque Controller 



31 



Three-Phase Power 
From Single-Phase Source 



By A. L. HOLCOMB 



Described is the development of a nonrotating device for the conversion of 
single-phase 115-v power to a three-phase 230-v form for the synchronous 
operation of cameras, sound recorders and other film pulling mechanisms 
associated with production of motion pictures. 



JL HREE-PHASE MOTORS provide several 
desirable characteristics which are not 
supplied by single-phase units of equiva- 
lent power, and these characteristics, 
which include smaller size, lighter 
weight and quieter performance, are of 
particular value for the operation of 
cameras in motion picture production. 
Unfortunately, three-phase power lines 
are seldom available for location work 
outside of the studio lot, whereas the 
single-phase, 115-v source has become 
readily available in a large percentage of 
locations. Since sound recorders can 
conveniently be driven by single -phase 
motors, due to higher permissible noise, 
and to less rigorous weight-space require- 
ments than cameras, it has become ap- 
parent that a synchronous converter 
from single-phase, 1 1 5-v, to three-phase, 
230-v, for camera operation would be 
a desirable device. This would permit 
the operation of all channel equipment 



Presented on April 25, 1952, at the So- 
ciety's Convention at Chicago, 111., by 
John G. Frayne for the author, A. L. 
Holcomb, Westrex Corp., 6601 Romaine 
St., Hollywood 38, Calif. 



from a single-phase source without 
degrading camera performance. 

A nonrotating device is preferable for 
reasons of noise and maintenance and 
while several such units are commer- 
cially available for this duty, they are 
not well fitted for camera drive since 
they require factory adjustment for the 
particular motor and load which the 
unit is to supply. Operation with 
other motors or different loads causes 
phase unbalance which can create 
operating noise and/or limit the maxi- 
mum power obtainable from the motor, 
thus destroying the very features for 
which a three-phase motor is desirable. 
Since most cameras used in motion 
picture production vary widely in power 
demand with temperature change, it. 
is only by chance that the factory ad- 
justed phase balance is optimum for 
any given location condition. If the 
maximum power condition of the motor 
is selected for phase balance, an un- 
balance and noisy operation exist for 
all lesser loads while adjustment for 
balance at light load reduces the maxi- 
mum power obtainable. 



32 



July 1952 Journal of the SMPTE Vol. 59 



TRANSFORMER T2 



SINGLE PHASE 

1 15V 
INPUT 




THREE PHASE 
LOAD 



TRANSFORMER Tl 



Fig. 1. Simplified schematic of the Converter. 



Thus, it appears that a satisfactory 
single-phase to three-phase converter 
for camera operation must provide 
either a circuit that does not unbalance 
when supplying different motors and 
varying loads, or one which provides 
some clear indication of unbalance and 
a ready means of correction which is not 
too complicated for field adjustment. 

Consideration of the problem indicates 
that the required phase shift from two 
conductors electrically 180 apart to 
three conductors displaced 120 cannot 
be obtained on a nonrotating basis 
without introducing reactance in various 
forms in the conversion circuit. Since 
the electrical load is also reactive, it 
will combine with the circuit reactance 
to determine the phase shift obtained 
unless isolation can be introduced be- 
tween the conversion circuit and motor. 
Adequate isolation does not appear to 
be practical because of space-weight 
and efficiency factors and thus the 
motor reactance which varies from 
motor to motor and with load on any 
given motor must be considered as a 
component part of the conversion cir- 
cuit. Therefore, a conversion circuit 
which will inherently maintain phase 
balance in the presence of the prescribed 
conditions is not considered practical, 
and as a result development has been 
focused on the alternative method, 
which would provide convenient indica- 
tion and adjustment. 



Basic Circuit 

The Scott transformer connection, 
which is relatively old in the art and 
described in most electrical engineering 
handbooks, is the basis of the conversion 
circuit shown in Fig. 1. This trans- 
former connection was originally used 
for the conversion of two-phase to 
three-phase or vice versa. By the 
addition of a capacitor of the right value 
in series with the primary of trans- 
former T2, as shown in Fig. 1, the cur- 
rent in this primary can be shifted 90 
with respect to the primary of Tl and 
thus the equivalent of a two-phase 
primary circuit is provided from a 
single-phase source. In the secondary, 
a three-phase electrical displacement 
exists only when connected to a balanced 
three-phase inductive load, which is the 
load condition presented by a three- 
phase motor. 

The circuit functions to produce 
120 phase displacement between the 
three output leads by means of the vector 
addition of both a proper voltage and a 
90 phase shift with respect to the 
mid-tap of Tl. A portion of the in- 
ductive load is reflected through T2 
where it is effectively resonated at line 
frequency by the series capacitor. This 
provides the 90 phase shift mentioned, 
since at resonance there will be no 
reactive component in the primary of 
T2 and the current will be in phase 



A. L. Holcomb: Three-Phase From Single-Phase 



33 




Fig. 2. Schematic of the Converter. 



with the voltage. The current in the 
primary of Tl will lag approximately 
90 since it is predominantly inductive. 
The secondary voltages of Tl and T2 
will thus be 90 out of phase and if the 
secondary voltage of Tl is made 230 
v and that of T2 is 200 v, then the 
voltage between the lead marked Phase 
1 and either Phase 2 or 3 will be: 
ri/2 + J'ETZ or 230 v. As combined in 
the load, the currents in all three phases 
are approximately 120 apart. 

From the above it becomes apparent 
why such circuits require adjustment to 
a specific load condition since a variation 
in either phase or voltage of the second- 
ary of T2 will upset the three-phase 
balance and both factors will vary with 
any change in impedance or inductance 
of the load. It also becomes apparent 
that this correction must provide a 
separate adjustment of the capacitor to 
match the load inductance in addition 
to a voltage correction for T2. 

Developed Circuit 

Development of the basic circuit for 
actual use is shown in Fig. 2. The 



transformers Tl and T2 appear in the 
same form as in Fig. 1, but the single 
capacitor is replaced by six units (C2 
to 7) of such sizes that they provide 
any value from 1 to 60 juf in \-yS. steps 
and are readily connected as required 
by means of individual switches. These 
are oil filled a-c capacitors rated at 
330 v. An additional capacitor shown 
as Cl is an a-c electrolytic unit of 
100-/zf capacity normally connected in 
parallel with the others through the 
relay SI. This is a necessary feature 
since the impedance of a synchronous 
motor is very much lower at the instant 
of starting than when running; there- 
fore, the capacitance required to ap- 
proach resonance at line frequency is 
several times greater at start than is 
desirable for running phase balance at 
even maximum load. Unless this initial 
high capacitance is provided, the output 
is essentially single-phase and the motor 
will not start. Gl meets this condition 
for the short start time and is auto- 
matically disconnected by the relay SI 
when the voltage across the primary of 
T2 reaches 100 v. The current supply 



July 1952 Journal of the SMPTE Vol.59 



to the coil of SI is rectified to avoid 
chatter of the relay contacts at break. 
The coil of relay S2 is in parallel with 
that of SI through a resistance which 
prevents operation of S2 unless or until 
the voltage rises to 300 v. This pro- 
vides protection for the running con- 
densers in case the load is disconnected 
while the operating switch Dl is closed. 
Opening the output circuit of phase 1 
allows the voltage of the resonant circuit 
in the primary of T2 to rise well above 
the condenser rating unless this pro- 
tection is provided. S2 in turn operates 
the relay S3 which opens the input 
circuit and locks up in this position 
until the input potential is removed. 

Tap changing on T2 was considered 
as an alternative method of resonating 
the primary with a single condenser, 
but this was abandoned since tap 
changing in such a resonant circuit 
causes excessive arcing, and because 
adjustment equal to that obtained by 
six condensers and switches would 
require a sixty-point tap switch. 

Voltage adjustment for T2 may be 
obtained without phase shift by means 
of series resistance in the resonant 
circuit or by resistance shunted across 
the primary of T2, but either method 
results in serious PR losses. The Variac 
T3 when connected across the input 
line, as shown, functions as an efficient 
voltage divider and does not contribute 
a reactive component to the resonant 
circuit since the exciting current is 
supplied by the line. Also, the range of 
adjustment is wide and very smooth. 

The three small voltmeters Ml, 
2 and 3 are the indicators used to 
determine and maintain phase balance. 
M2 is a 150-v meter connected across 
the incoming line which serves as a 
pilot meter on the single-phase supply, 
and also effectively indicates the voltage 
across phase leads 2 and 3 during 
operation since this voltage is twice the 
line voltage except where a heavy load 
may introduce appreciable PR loss in 
Tl. Ml and M3 are 300-v meters 



across the other two output phases. 
With this arrangement, both three- 
phase output and single-phase input 
are shown in addition to the basic 
function of balance indication. 

Adjustment and Operation 

The selection of the proper capacitance 
in the primary circuit of T2 need only 
be determined once for any given motor 
and line frequency. Therefore, this 
information may be obtained in the 
shop before the camera goes on the set 
or location. Once obtained, the con- 
denser values for different motors, or 
combinations of motors, may be tabu- 
lated and attached to the converter 
for ready reference. 

To determine capacitor value, the 
motor is connected for operation, pref- 
erably driving a camera or other normal 
load. The condenser values of 1, 2, 
4, 8, 15 and 30 /-if are marked on the 
plate adjacent to the switches which 
connect them in parallel. Thus, the 
values shown are additive as the switch 
handles are toward the marked plate. 
About 25 /uf should be connected as a 
preliminary value of capacitance for 
60-cycle operation (approximately 35 
juf for 50-cycle). The Variac is posi- 
tioned about center and the motor 
started by closing the "line" switch Dl. 
The two outside meters Ml and 3 are 
then observed and the Variac adjusted 
until they read alike. If this balanced 
reading is higher than the pointer 
position of the middle meter M2 (twice 
the indicated voltage) then the capaci- 
tance should be reduced, or vice versa, 
and Ml and 2 again balanced by 
Variac adjustment. This is continued 
until all three meters show the same 
pointer position. With very little prac- 
tice this adjustment can be accomplished 
in less than a minute. Having estab- 
lished and noted the capacitor value 
the unit is ready for operation; further 
adjustment for load variation being 
made by changing the Variac to make 
the pointer of Ml read the same as 



A. L. Holcomb: Three-Phase From Single-Phase 



35 




TRANSFORMER 
PRIMARIES 



SOLID LINES = NO MOTOR LOAD 
DOTTED LINES = IOOW MOT.OR LOAD 




30 OUTPUT 
Fig. 3. Phase-voltage relations without load correction. 



1 15V 




TRANSFORMER 
PRIMARIES 



SOLID LINES = NO MOTOR LOAD 
DOTTED LINES = I60W MOTOR LOAD 



36 



30 OUTPUT 

Fig. 4. Phase-voltage relations with load correction. 
July 1952 Journal of the SMPTE Vol.59 



M2 a few volts. In either initial 
or subsequent balancing, it will be found 
that both Ml and M3 vary in the same 
direction with each other and with the 
Variac. However, Ml, across phase 1 
and 2, varies more rapidly than M3, 
and M2 does not change except with 
input voltage. 

In operation, the converter may be 
located at the camera and the "line" 
switch Dl used as the camera operating 
switch, or the unit may be positioned 
at the recorder with any individual or 
common switching desired. In mild 
weather where temperature and camera 
load do not vary greatly, the initial 
load adjustment of the Variac might 
well remain the same for several days 
shooting. In case of cold weather, 
however, some cameras will warm up 
enough in a long take to change load 
by a factor of 2 or 3. Adjustment of the 
Variac to meet this condition may be 
made during a take without disturbance 
to either picture or sound. It should 
be noted, however, that precise adjust- 
ment is not essential to operation and 
under average conditions the unit can 
be forgotten unless the camera motor 
becomes noisy or lacks power. 

Where recorder and camera are 
both operated from the converter, either 
motor may be dropped off at will. The 
phase balance will be materially upset 
and the remaining motor will be noisy 
but the recorder is usually too far from 
the microphone to cause trouble, and 
if the recorder is cut off, the camera noise 
does not matter. 

Performance 

It is obvious that the voltmeters used 
as indicators of phase balance actually 
show only voltage across the three phases 
and indicate phase relation indirectly 
if at all. Thus, this method of indica- 
tion may well be questioned. Since 
the voltages indicated are each a re- 
sultant of two voltages to the mid-point 
of the load, which in turn are the 
resultant of a vectorial addition of both 



voltage and phase relation, the theo- 
retical reasons why such indications are 
of value become involved and tedious 
and will be omitted in favor of measured 
results. 

A true picture of the voltage condi- 
tions in the load can be obtained by 
measuring the voltage from each phase 
lead to a mid-tap on a star connected 
load. In addition, a method was 
devised which indicated voltage phase 
relations across the same points, and 
across Tl and T2 primaries, to an 
accuracy of db. The currents in 
each leg of the load are not in phase 
with the voltage but bear the same 
relation to each other as the voltages 
since the load is electrically symmetrical. 
With the above arrangement, it was 
possible to obtain an accurate picture 
of phase-voltage relations under varying 
load conditions. 

A motor fairly typical of three-phase 
synchronous camera motors was oper- 
ated through the converter from a 
115-v single-phase source and adjusted 
for capacitance balance at no-load in 
the manner previously outlined. The 
accuracy of balance in each case was 
probably of the order of 2 v; about 
what would be expected in normal use. 

Figure 3 shows the phase-voltage 
relations without correction for load 
change. In Fig. 3A the primary of T2 
is compared to the primary of Tl which 
latter is also the line input and does 
not change with load. The solid line 
shows T2 at 140 v displaced 89 from 
Tl when the motor ran no-load. When 
the load was increased to just under 
pull-out, the voltage dropped to 112 v 
across T2 and the phase relation to 
Tl became 75 as shown by the dotted 
line. In Fig. 3B of the same figure is 
shown the resultant conditions existing 
in each phase winding of the motor. At 
no-load as again shown by the solid 
lines, the voltages to the mid-point 
were between 131 and 134 v with 
phases 121, 121 and 118 apart. With 
100-w load on the motor, phase 1 has 



A. L. Holcomb: Three-Phase From Single-Phase 



37 




Fig. 5. Engineering model of the Converter. 



dropped to 104 v and shifted to 107 
from phase 1 and 131 from phase 3, 
phase 2 has dropped to 118 v while 
phase 3 has shifted 4 and increased 
voltage slightly. As a result, the motor 
was noisy and the maximum stable 
power obtainable was reduced from 
160 w mechanical to 100 w or 62 \% 
of normal. This was chiefly due to the 
changes in phase 1 with some con- 
tribution from the reduced voltage in 
phase 2; the voltage change and phase 
shift of phase 3 being of little importance. 
In this connection it was found that 



unbalance of 10 v between phases, or 
5 to 6 departure from the ideal, did 
not create noticeable noise or power 
reduction unless these factors combined. 
Figure 4 is similar to Fig. 3 except that 
correction for increased load was made, 
as described, by means of the Variac T3. 
In Fig. 4A the phase shift and voltage 
change in the primary of T2 is small, 
being 2 and 4 volts, respectively. In 
Fig. 4B the phase shift in the motor 
windings is negligible (3 maximum) 
although some voltage unbalance exists 
due to an increase in voltage of phase 



38 



July 1952 Journal of the SMPTE Vol.59 



2 while phases 1 and 3 are reduced 
alike. This unbalance is not too serious 
and it appears only when capacitance 
balance has been made at no-load and 
load correction has been stretched to 
cover the whole power range of the 
motor. It should be noted in this 
connection that the motor load is 
160 w under the conditions of Fig. 4 
which is the same maximum power 
which this motor can deliver from a 
normal three-phase line. 

Power Characteristics 

Power output capacity sufficient to 
handle any motor or combination of 
motors would be desirable. Since this 
cannot be provided in a portable device, 
the maximum weight which can be 
carried by one hand (about 50 Ib) was 
used as a base, and as much power as 
possible was provided within this limi- 
tation rather than selection of some 
arbitrary value of power. The result 
of this approach is a power output of 
about 400 va; the real watts and 
available mechanical power being deter- 
mined by the power factor and efficiency 
of the motor. The engineering model 
is shown in Fig. 5. 

The single-phase input power factor 
is relatively good and varies from 50 
to 95%, while the conversion efficiency 
from single-phase to three-phase varies 
from 30 to 75%; both factors depending 
on the characteristics of the motor load. 

In terms of equipment which can be 
operated by the converter, the following 
motors or combinations of motors appear 
to be within the power handling range 
of the unit: 

Standard camera, synchronous motor 

limited only by motor power 
Standard camera and portable recorder, 

synchronous motors above 50 F 

ambient 
Standard camera and portable recorder, 

multiduty motors any weather 



Technicolor camera above 50 F 
ambient 

As previously noted the load demand 
of most cameras varies widely with 
ambient temperature and the weather 
is thus noted as a limiting load factor 
in some cases. Multiduty motors * oper- 
ated in the synchronous mode function 
at relatively high efficiency and good 
power factor and thus heavier loads 
and/or more motors are operable from 
the converter than is the case with the 
usual variable reluctance synchronous 
type. It should be noted that the 
inclusion of this converter in a multi- 
duty equipped channel adds single- 
phase, 115-v supply to the existing 
battery and three-phase power sources 
frpm which such channels can operate. 

Conclusion 

The development of a portable, non- 
rotary converter to supply three-phase, 
230-v from a single-phase, 115-v source 
has seemed desirable in order to realize 
the inherent advantages of three-phase 
motors, particularly on motion picture 
cameras, while utilizing the convenience 
and availability of single-phase source 
of supply. Good phase-voltage balance 
is essential in such a device under vari- 
able load conditions, and it has been 
possible to obtain this by providing a 
simple form of indication together 
with a ready means of correction. 

Discussion 

William P. Kruse: Approximately what 
is the primary voltage on your resonant 
transformer during some various normal 
loads? 

(Communicated by} A, L. Holcomb: The pri- 
mary voltage of T2 is maintained essentially 
constant at 135 volts by adjustment of the 
Variac, as described, to meet the various 
load conditions. 



* A. L. Holcomb, "Motor systems for 
motion picture production," Jour. SMPE, 
42: 9-33, Jan. 1944. 



A. L. Holcomb: Three-Phase From Single-Phase 



39 



Continuous Arc Projector 
Light Meter 

By HARRY P. BRUEGGEMANN 



This is a system for monitoring the light output of an arc projector during 
projection. It comprises a piece of optically flat glass, not silvered, placed in 
the projector light path, at an angle of 45, and ahead of the film gate. The 
light thus thrown off to the side is measured by a photovoltaic light meter. 



.RC PROJECTORS are normally built 
for theater projection, and they are 
designed to give a picture of pleasing 
quality. However, when arc projectors 
are used as laboratory production 
equipment for timing prints or for side- 
by-side comparison of prints, they must 
meet certain rigid specifications. One 
of these is the maintenance of an abso- 
lutely steady light output. 

Experience at Cinecolor has been 
that arc projectors vary in their light 
output by as much as 20% during a 
10-min projection, in spite of good 
operational practices and frequent equip- 
ment maintenance. This variation, of 
which the projectionist has no indication, 
seems to be due to the carbon feed, 
slight imperfections in the carbons 
themselves, voltage fluctuations and 
mechanical variables. A 20% change 
in light output would probably never 

Presented on April 22, 1952, at the So- 
ciety's Convention at Chicago, 111., by 
George W. Colburn for the author, 
Harry P. Brueggemann, Cinecolor Corp., 
2800 W. Olive Ave., Burbank, Calif. 



be noticed in a theater, provided it is 
gradual enough. To a timer though, 
who is attempting to adjust scene 
densities to within one-half of a printer 
point of what the producer wants, a 
change of this magnitude is too great. 

A number of systems for controlling 
the arcs were investigated. One such 
system consisted of a photoelectric cell, 
the output of which would control a 
thyratron, which in turn would control 
the carbon-feed motor in such a manner 
as to maintain a constant luminosity. 
This has the advantage of being auto- 
matic, the control being maintained 
without requiring an adjustment by the 
projectionist. As far as could be de- 
termined, there was no such thyratron 
arc controller on the market, hence it 
would have to be designed. Since 
Cinecolor already had some experience 
in designing thyratron controlled light 
sources, it was realized that this under- 
taking would be very expensive. All 
types of photoelectric light meters were 
eliminated, also, because of design 
expense. 



40 



July 1952 Journal of the SMPTE Vol.59 



The only system which seemed feasible 
would make use of a photovoltaic cell 
type of meter so arranged as to keep 
the projectionist continually informed 
as to the light output of the projectors. 
With this guide, he could maintain the 
light at the standard value by trimming 
the arc. A photovoltaic cell is practical 
because it maintains its calibration 
quite well if protected from heat, 
moisture and intense light. Since a 
great deal is known about the use of 
photovoltaic cells as light meters, design 
of such a system should be relatively 
simple. 

Accordingly, a projector light meter 
was built around a photovoltaic cell. 
In order to monitor the light actually 
reaching the screen, a piece of unsilvered, 
optically flat glass was placed in the 
light path at an angle of 45. This 
threw a beam of light off to the side of 
the projector, amounting to approxi- 
mately 10% of the total output. This 
was more than enough for any photo- 
voltaic cell, and at the same time caused 
a loss of only 10% in the screen bright- 
ness. This could be compensated for 
by trimming the arc. Obviously, the 
glass had to be positioned between the 
arc and the film gate. 

The photocell was a Weston Photronic 
cell type RR, and the associated am- 
meter was a to 20-/*a, 2500-ohm 
Weston meter. Since the light from 
the optical flat was far too much for 
the cell, a means of attenuating this 
light was necessary. A dense green 
glass was placed ahead of the cell in the 
first model. This cut down the light 
to a workable level, but permitted a 
great deal of infrared radiation to be 
transmitted. This infrared energy 
raised the temperature of the cell too 
high for stability, so an Aklo heat glass 
was added. This promptly cracked. 
Thus it was evident that another means 
of reducing the heat was necessary. 
Ventilation slots were cut into the 
casting holding the cell, and this helped 



some, but the Aklo glass still would not 
stand up. 

At this point the projectionists at the 
M-G-M laboratory, who had been in- 
formed of our project and had built a 
model of their own, thought of replacing 
the dense glass filter by a sheet of brass 
shim stock with pinholes. This solved 
the excess heat problem, since the 
infrared radiation was reduced as much 
as the light. The first Cinecolor model 
used a bakelite mounted photocell, but 
M-G-M used a metal-encased cell for 
conduction cooling. The M-G-M modi- 
fications resulted in a cell mounting 
which was only slightly warm to the 
touch, even after many hours of con- 
tinuous operation. 

The Weston microammeter, with its 
2500-ohm resistance, gave a fairly 
linear response when coupled to the 
type RR Photronic cell. Various de- 
vices were considered for improving 
the linearity, including shunt resistances, 
lower resistance ammeters, and other 
types of photocells; but they all re- 
quired more light, and consequently 
would have placed more heat at the 
photocell. Since heat dissipation was 
the biggest problem of the project, it 
was decided to accept the slight non- 
linearity. The only advantage to im- 
proving the linearity would be to 
eliminate the scale compression in the 
operating range and thus increase the 
sensitivity. With the present model of 
the meter, however, luminosity fluctua- 
tions can be kept within about 3% and 
this is considered good. Most of this 
fluctuation is due to the coarseness of 
the trim, not the accuracy of the meter. 

The location of the unit in the pro- 
jector is shown in Fig. 1. This view 
shows the first Cinecolor model mounted 
in a Simplex projector, just above the 
framing knob. The rear end of the 
photocell, showing the bakelite casing, 
is seen together with the two wires 
leading to the microammeter. The 
ammeter is mounted on the wall of the 
projection booth just below the viewing 



Harry P. Brueggemann: Continuous Arc Projector Meter 



41 




Fig. 1. View of the first Cinecolor model mounted in a Simplex projector. 



THREAD- UP LAMP 
HOUSING 




-PHOTOCELL 



ATTENUATOR 

GROUND GLASS 



MtCROAMMETER 




42 



Fig. 2. The three basic units of the second Cinecolor model. 
July 1952 Journal of the SMPTE Vol. 59 



r-REFt-Ecr.- 




\ 



Fig. 3. Schematic of system top view. 



port, so that the projectionist can see 
the screen and the meter at the same 
time. Figure 2 shows the three basic 
units of the second model the optical 
flat and brass attenuator mounting, 
the metal-encased photocell, and the 
microammeter. The optical flat occupies 
the space normally used by the thread-up 
lamp when it is lowered for threading 
up. The lamp was repositioned so that 
it missed the optical flat when lowered. 
The perforated brass attenuator slides 
into a slot cut just ahead of the photocell 
housing. The edge of the attenuator is 
visible in the figure. There is a ground 
glass immediately behind the attenuator 
to break up the light through the pin 
holes, and thereby avoid any local 
"hot spots" on the surface of the photo- 
cell. Figure 3 is a schematic drawing of 
an arc projector with the unit installed. 
In operation, the system requires only 



a 5-min warm-up period in the morning, 
after which it will remain constant all 
day. The warm-up is necessary because 
the photocell has greater sensitivity 
when cold, and temperature equilibrium 
must be reached before the system 
stabilizes. During projection, the opera- 
tor needs only to keep the needle at a 
constant standard value by appropriately 
trimming the arc. The use of this 
system has resulted in a great improve- 
ment in projection quality, both at 
Cinecolor and M-G-M. 

Thanks are expressed by the author 
to James Phillips, Chief Projectionist at 
Cinecolor, for initiating and doing most 
of the original work in this project, 
and at M-G-M to Merle Chamberlain, 
Chief Projectionist, and Clayton C. 
Troxel, Jr., Projection Engineer, for 
their modification which contributed to 
the success of the final model. 



Harry P. Brueggemann: Continuous Arc Projector Meter 



43 



Use of a Rotating-Drum Camera for 
Recording Impact Loading Deformations 

By D. F. MUSTER and E. G. VOLTERRA 



The details of a rotating-drum camera are described. The camera is used to 
record displacement-time data for short cylindrical specimens made of a 
rubberlike material which are subjected to compressive impact loadings 
lasting from 5 to 20 milliseconds. The auxiliaries to the camera are discussed 
in light of the particular needs of a study being conducted on the dynamic 
properties of plastics and rubberlike materials. 



LN INVESTIGATION on the dynamic 
stress-strain properties of plastics and 
rubberlike materials is bein conducted 
at Illinois Institute of Technology under 
the sponsorship of the Mechanics Branch, 
Office of Naval Research, as part of 
their basic research program on the 
properties of materials. 

For determining directly the stress- 
strain curves of plastics and rubberlike 
materials subjected to impact loads, 
the duration of which are of the order 
of milliseconds, a special apparatus has 
been built which uses mechanical and 
optical devices. The paper is confined 
to only a brief description of the optical 
parts of the apparatus, and particularly 
of a special rotating-drum camera and 
its accessories which is used to record 
displacement-time data for the speci- 
mens being tested. 

The apparatus employed in the experi- 
ments is shown in Figs. 1, 2 and 3. It 
consists essentially of: 



Presented on April 23, 1952, at the So- 
ciety's Convention at Chicago, 111., by 
D. F. Muster and E. G. Volterra, Dept. 
of Mechanics, Illinois Institute of Tech- 
nology, Chicago 16, 111. 



(1) two 3-ft, 1-in. diameter steel 
bars, of equal mass, suspended as 
ballistic pendulums; 

(2) a rotating-drum camera, the drum 
of which rotates at a known speed, and 
the shutter of which is synchronized to 
operate with the motion of the steel 
bars; 

(3) an optical system which focuses 
the image of a very thin slit on the knife 
edges machined on the adjoining ends 
of the steel bars; and 

(4) an electromagnetic device which 
can release one or both of the bars at 
the same time. 

The cylindrical specimens of plastics 
or rubberlike materials to be tested are 
\ in. in diameter and \ in. long. They 
are placed on the plane end of one of the 
steel bars such that the longitudinal 
axes of the bar and of the specimen 
coincide. The other steel bar is released 
from a predetermined height by a 
magnetic release mechanism and is 
made to impinge upon the free end of 
the specimen. During the impact a 
photograph is taken of the interval 
between the knife edges which lie in 
the plane of the ends of the steel bars. 



44 



July 1952 Journal of the SMPTE Vol.59 




Fig. 1. Front view of camera. 



A,. Push Button Control 
E. Projection lAap Switch 
C.,Blowr Motor Switch 
D . .Tflyratron Extinguish 

Control 
E. Delay Clrcait, Fii 



F,. Camera Motor Switch 
G,. Belay Circuit Switch 




Fig. 2. Back view of camera. 
Muster and Volterra: Use of a Rotating-Drum Camera 



45 



MICROSWITCH 

O- 



BAR- 



V 
PIVOT 




(on camera) 



Fig. 3. Schematic diagram of equipment arrangement. 



The magnetic release mechanism is 
controlled electrically by a cam device 
(shown on the camera shaft in Fig. 1), 
which serves to time the release of the 
bar with the position of the film on the 
drum. This insures that the exposed 
strip of film will not include the overlap 
region where the two ends of the film 
are joined. 

A delay circuit is adjusted so as to 
cause the shutter mechanism to operate 
during the time interval of from 5 to 
20 msec during which the impact 
between bar and specimen occurs. The 
record on the film strip is calibrated by 
superposing a still photograph of the 
distance between the two knife edges 
when both bars are just in contact 
with the specimen. 

The data on the film strip are read 
by direct measurements made with a 
microscope mounted on a movable base. 
The base is fitted with two orthogonal 
motions and can transverse a maximum 
of 4.5 in. in increments of 0.001 in. 
From these data the displacement-time 
relationship is plotted. 

The camera body is made of J-in. 
thick aluminum alloy plates. Front 
and back views of it are shown in Figs. 
1 and 2. All joints have been sealed 



and the entire assembly painted dull 
black. The back of the camera body 
is mounted on hinges which permit easy 
access to the drum. The back is 
locked in position by four trunk-type 
fasteners and is light sealed by a i^-in. 
thick neoprene gasket cemented to its 
inside surface. 

The drum was turned from a 2-in. 
cold-rolled steel plate and its finished 
dimensions are indicated in Fig. 4. 
It is mounted in the camera on a keyed 
shaft with a large hex nut to facilitate 
easy removal in the dark. The film 
is placed on the inner surface of the 
drum and held in position by two spring- 
metal strips which grip the film strip at 
its edges. The drum accommodates a 
48-in. length of film, which permits a 
slight overlap, and there is a useful 
length of approximately 40 in. of film. 

In the drum periphery there are two 
f-in. radial holes that are used to focus 
the slit image on the film strip. There 
is a corresponding hole fitted with a 
sealing flap in one end of the camera 
body. 

The drum- is driven by a small induc- 
tion motor rated at ^ hp at 900 rpm. 
Through a belt and pulley arrangement, 
the speed of the camera drum is reduced 



46 



July 1952 Journal of the SMPTE Vol. 59 



15.13" DIAM FROM FILM TO FILM. 




j" DIAM 
HOLE 



0.13" 



Fig. 4. Rotating drum. 




TOP VIEW 



Fig. 5. Schematic diagram of optical system. 



P.... Projection Lamp, GE 750T12P 

G . . . Ground-Glass Plate, 2 in. X 3 in. 

S... .Slit, 0.001 in. X | in. 

K. . .Knife Edges on bars 

M. . .Mirror, first-surface set at 45 to axis 
of lens arrangement 

F . . . . Film, Kodak Linagraph Panchro- 
matic LP421 



LI. . .Condensing Lens, 6in. //1, 4 ^in.diam 
L2 ... Projection Lens, 75mm //I, 49mm 

diam coated achromat 
L 3 . . .Piano Convex Field Lens, 17 in. //I, 

3^ in. diam 
L4. . .Piano Convex Field Lens, 21 in. //I, 

3^ in. diam 
L 6 . . .Camera Lens, Color Skopar// 3.5, 105 

mm //I 



Muster and Volterra: Use of a Rotating-Drum Camera 



47 



to about 120 rpm, an adequate speed 
for the shortest time during which 
impact occurs. The actual speed of 
the drum is measured just before and 
after each test by means of a Jagabi Speed 
Indicator accurate to within i of 1%. 

The optical system from light source 
to film on the camera drum is shown in 
Fig. 5. There is every possibility that 
other equivalent systems could be 
designed; however, the one shown in 
the figure was developed from the equip- 
ment and materials most readily at hand 
after a trial-and-error period in which 
the design was changed several times. 

The light source (not shown in Fig. 1) 
is mounted in the air stream of a centrif- 
ugal air blower immediately behind the 
cylindrical tube which contains the 
condensing lens, ground-glass plate, 
slit, and projection lens, in that order. 
The impact phenomenon occurs be- 
tween a pair of field lenses, the first of 
which serves to collimate the light rays 
and the second, to focus the collimated 
rays on the surface of the objective 
lens. The light path between the field 
lenses is partially blocked by the knife 
edges on the bar ends, the distance 
between the edges at each instant of 
time indicating the deformation in the 
specimen. 

The camera lens, a Color Skopar I, 
//3.5, 105-mm coated lens, focuses 
the slit image on the film by means of 
a first-surface mirror set at 45 to the 
axis of lens arrangement. The image 
is brought into focus by viewing it on 
a piece of exposed film set over the 
holes in the drum and the camera case 
(see Figs. 1 and 2). 

There are two electronic circuits 
which are important to the proper 
operation of the camera: 

(1) the timing circuit of the bar 
release mechanism; and 

(2) the shutter delay circuit. 

The former operates through a cam on 
the shaft of the camera and times the 
release of the impinging bar so that the 
exposed strip of film will not include the 



region of the splice. In order that the 
bar will be released two contacts must 
be closed, a pushbutton controlled by 
the laboratory technician and the cam 
timing contact which is preset. It is 
expected that the bars will have essen- 
tially the same periods from release to 
initial impact for all anticipated values 
of drop height. Thus, the cam setting 
should not have to be changed, except 
for minor adjustments, until very large 
drops are attempted. 

The shutter delay circuit, as its name 
implies, causes the shutter mechanism 
to open the shutter just prior to the 
instant of initial impact. The actual 
exposure time is governed only by the 
speed of the drum and is preset on this 
basis. 

Thus far, Kodak Linagraph Pan- 
chromatic LP421 film and Dektol 
(D-76) developer have been used with 
good results. 

Summary 

The rotating-drum camera described 
here has been built to record an impact 
phenomena, which occurs in from 5 to 
20 msec, in order to determine directly 
some of the dynamic properties of 
rubberlike materials at high rates of 
compressive straining. The optical ad- 
vantages of a one-to-one slit-image relay 
system are utilized to produce, on a 
film strip, direct displacement-time data 
which could not be obtained by any other 
means. 

Electronic circuits are provided to 
time the release of the ballistic pendulums 
with the proper position of the film 
in the camera and to delay the opening 
of the shutter until just before the 
instant of initial impact. 

Acknowledgment 

The authors wish to thank R. E. 
Lewis, Physicist, Armour Research 
Foundation, and R. A. Einweck and 
C. R. Olson, Illinois Institute of Tech- 
nology, for their help on this and other 
phases of the project. 



48 



July 1952 Journal of the SMPTE Vol. 59 



The Navy's Training Film Production Program 

And a Description of U. S. Naval Photographic Center 
Film Depository Facilities Available to Commercial Film 
and Television Agencies 



By WILSON R. GRONENWETT and WILLIAM M. TIMMONS 






The production of a motion picture is traced from the request stage through 
the Navy Film Board of Review, to production by either commercial con- 
tractor or the Navy Photographic Center. Film distribution is described, 
and also the special photographic services available to the film and television 
industries by the Naval Photographic Center's film depository. 



T. 
HE NAVY'S film production program 

grows out of a need. The Navy has 
many training schools, special activities 
and, of course, the fleet. In all these 
places men must be trained efficiently 
and effectively in the skills and knowl- 
edges of Navy work. These are in- 
tensely practical needs. 

In the past, the apprentice system 
has been an excellent method of meeting 
such needs. An inexperienced man 
worked alongside a trained man and 
gradually gained the same skills and 
knowledge through observation, active 
learning and correction of mistakes 
pointed out by the trained man. The 
apprentice system, however, was slow, 

Presented on April 22, 1952, at the So- 
ciety's Convention at Chicago, 111., by 
LCDR Wilson R. Cronenwett, USN, 
Head, Motion Picture Branch, U.S. Naval 
Photographic Center, Anacostia, D.C., 
and Dr. William M. Timmons, Educa- 
tional Adviser, Naval Photographic Center. 



could be used only for training a rela- 
tively small number of men. Necessary 
skills and knowledge in such highly 
technical and complex fields as elec- 
tronics and fire control also proved the 
inadequacy of the apprentice system. 
The untrained man could not learn 
these complex skills and knowledge by 
observation. He could work beside 
the experienced man for many months 
without learning more than the super- 
ficial aspects of the work. Too much 
was hidden from direct view, or there 
was so much to view that one couldn't 
interpret it. 

The training film, along with other 
aids and methods, has solved the train- 
ing problem. It has many of the merits 
of the apprentice system, while at the 
same time permitting observation of 
those things which are normally hidden 
or which are cluttered up in a maze of 
detail. It is equally useful for teaching 
simple skills and techniques, and highly 



July 1952 Journal of the SMPTE Vol. 59 



49 



complex and technical ones. More- 
over, it can effectively and rapidly 
teach many men simultaneously. 

This was the need that had to be met 
during World War II. It was a big 
need and was not met all at once. The 
program grew. In the summer of 
1941 the staff to meet the need con- 
sisted of one junior officer. By 1945 
over one hundred officers were supervis- 
ing the production of films. The Photo 
Science Laboratory had its own staff of 
writers, cameramen, editors, and tech- 
nicians. There were about 30 training 
aids libraries and about 70 officers advis- 
ing on film utilization. By early 1945 
over 1000 motion pictures had been 
produced, as well as 2500 slide films. 
Close to a million prints had been 
distributed. 

The films produced were good, bad, 
and indifferent. A surprising number 
were superior. All contributed to the 
practical job of training many officers 
and men in Navy skills and information. 
That they were generally good is due 
to a number of factors. The Navy 
leaned heavily on many small com- 
mercial producers who had developed 
considerable know-how in producing 
films for business and industry prac- 
tical films, often training films. The 
officers recruited as project supervisors 
came from two primary sources, the 
film industry and education. They, 
with the small commercial producers, 
made Navy films what they were. 

The project supervisors with their 
diverse backgrounds were a source of 
ideas, methods and procedures, as well 
as of disagreements. They did not 
solve all the problems of how to make 
films that do the practical teaching job. 
But out of the ferment of the war-time 
group there came at least these results: 

(1) A set of production procedures 
were worked out. (These are still used.) 

(2) Production control procedures 
were developed. (These are still fol- 
lowed, with refinements.) 



(3) Emphasis was placed on a new 
type of film, one designed to teach rather 
than to entertain. 

We knew what we wanted but we 
did not know all the techniques of 
making films that teach. We still do 
not know, but we have made progress. 

On the basis of this background, I 
want to indicate how the Navy's film 
needs are met today what the pro- 
gram is today. There are three basic 
aspects to the program: production, 
distribution and procurement. 

Production 

The overall responsibility for film 
production in the Navy is in the hands 
of the Bureau of Aeronautics, Photo- 
graphic Division. Production super- 
vision and control are delegated to the 
U.S. Naval Photographic Center. All 
training films are therefore produced 
in their entirety at NPC or are pro- 
duced commercially under the Center's 
supervision. In either case they are 
produced in close coordination with that 
part of the Navy desiring the film. 

Although we have the usual adminis- 
trative personnel to keep the entire 
program moving and an educational 
specialist to insure that each film does 
its intended teaching job, the key people 
on any production are two in number. 
One is the project supervisor, repre- 
senting the Naval Photographic Center. 
The other is the technical adviser 
representing the Naval activity, school, 
Bureau or fleet unit wanting the film. 

The project supervisor acts as the 
producer of his assigned projects. He 
may be responsible for as many as twenty 
projects at one time. He is responsible 
for planning, scheduling and super- 
vising all except purely technical aspects 
of his projects from initial request to 
final acceptance of the training film. 
He must make sure that each of his films 
does the intended teaching job, is right 
as a motion picture, and is made within 
the allotted budget. He must judge 
the work of script writer, graphics 



50 



July 1952 Journal of the SMPTE Vol. 59 



specialist, camera man, director, editor, 
animators, sound technicians and proc- 
essing technicians. Naturally he leans 
on others to the extent needed, but his 
is the final responsibility. 

The technical adviser is an expert 
in the content of the film. His basic 
responsibility is to make sure that the 
script and the resulting film are tech- 
nically accurate and technically com- 
plete in all details. In addition, he 
must make sure that incidental things 
shown are right, that approved safety 
procedures are followed, that all clothing 
is properly worn, that security regula- 
tions are followed in what is shown, 
and that even little things like haircuts 
are strictly Navy. 

The training film which these two 
individuals, project supervisor and tech- 
nical adviser, work on may be any one 
of several types: motion picture, photo- 
graphic report, public information film, 
slide film or filmagraph. While this 
classification may sound illogical, the 
terms have grown in response to the 
Navy situation. Some of the terms are 
self-explanatory. Others need a word 
of explanation. A motion picture is 
any carefully planned, complete motion 
picture production, in live action or 
animation, designed for training pur- 
poses. A film on How to Get Usable 
Motion Picture Footage falls into this 
category. A photographic report con- 
sists of motion picture coverage of an 
actual operation or activity put together 
in the best way possible to give general 
professional information to Naval per- 
sonnel. A film showing an actual 
amphibious landing, covered photo- 
graphically as well as circumstances 
permit, is a photographic report. A 
public information film is any motion 
picture telling the public about any 
part of the Navy. The slide film needs 
no definition. The filmagraph is essen- 
tially the same as a slide film except 
that the still pictures and the sound are 
put on motion picture stock, and the 
resulting film is projected on a standard 



sound motion picture projector. With 
careful planning, standard opticals and 
the use of popped-on or dissolved-on 
items or labels, camera trucks and 
simple pans, the filmagraph becomes a 
simulated motion picture. For certain 
kinds of content, where continuous mo- 
tion is unimportant or where motion 
can be simulated by simple techniques, 
the filmagraph is an excellent, low-cost 
teaching film. We have used the 
filmagraph, for example, to show how 
to bend oak timbers and to explain the 
Navy's part in our Revolutionary War. 
In the Navy the filmagraph has largely 
replaced the slide film. 

During the fiscal year now ending, of 
the films going into production 72% 
were motion pictures for specific train- 
ing purposes, 10% were photographic 
reports for general training purposes, 
less than 2% were public information 
films, 16% were filmagraphs for specific 
training purposes, and none were slide 
films. 

Thus, Navy production consists pri- 
marily of films for training. These films 
follow a general pattern of production. 
At the outset someone in the Navy has 
a training problem which he thinks 
can be solved by a film. In consultation 
with a representative of his parent Navy 
Bureau and an educational specialist 
from the Naval Photographic Center a 
decision is made that a film will or will 
not help solve the training problem. 
If it is agreed that a training film is 
desirable, they prepare a production 
outline. The production outline is a 
detailed analysis of who will see the 
film, what the audience already knows, 
what they should know or be able to 
do after seeing the film, the content to 
be included, the technical photographic 
specifications and shooting locations. 
In other words, the production outline 
includes the basic specifications on which 
the script and film will be based. Every 
effort is made at this stage to insure 
that only needed films are requested 



Cronenwett and Timmoni: Navy Training Film Production 



51 



and that the requested film will be a 
good teaching film. 

The production outline is submitted 
to the Navy Film Production Board 
of Review. This board is made up of 
officers representing the training and 
fiscal parts of the Navy. They deter- 
mine what training films are to be 
produced, the priority and the basic 
specifications for each film. For a 
film to be approved, the need must be 
justified, the plan must appear educa- 
tionally sound and the project must 
represent a wise expenditure of public 
funds. 

If the Navy Film Production Board of 
Review approves the project, the Bureau 
of Aeronautics assigns it to the Motion 
Picture Branch of the Naval Photo- 
graphic Center for production. It 
becomes either an NPC production 
done entirely with NPC facilities or an 
NPC contract production done with the 
assistance of a commercial studio. Pro- 
ductions done entirely at the Center are 
normally those of the highest security 
classifications or those requiring shooting 
on location or intermittent photography 
that cannot be done efficiently by 
commercial studios. 

Regardless of how the film is to be 
produced, the Photographic Center as- 
signs the project to one of its twenty 
project supervisors. The requesting part 
of the Navy assigns a technical adviser. 
These two individuals supervise the 
preparation of a script. In all cases 
where art or animation is to be included 
in the film, the script includes a de- 
tailed storyboard. The resulting script 
must be more than technically correct. 
It must be capable of being produced at 
a reasonable expenditure of time and 
money. Expensive color is used only 
if it will contribute to the teaching 
quality of the film. The comparatively 
inexpensive filmagraph is used rather 
than the motion picture if the former 
will accomplish the film purpose as 
effectively. If a short film will do the 
job, no padding out is permitted. The 



script must be consistent with the speci- 
fications laid down by the Navy Film 
Production Board of Review, in accord 
with governmental policy and in good 
taste in all respects. It must lend 
itself to becoming a good film from the 
point of view of direction, photography, 
editing and sound. Above all it must 
be educationally valid. 

It is on the educational side that 
we are making perhaps our most out- 
standing contribution. Emphasis on 
educational effectiveness is placed at the 
script stage. If the script is educa- 
tionally sound and if the production 
follows the script, there will be little 
difficulty in making the resulting film 
educationally sound. 

We shall not discuss our educational 
standards in detail here, but it may be 
helpful to indicate a few of the general 
principles followed. The scriot should 
make the learner aware of what is 
expected of him. The script should be 
carefullv organized around the chief 
instructional values to be gained from 
the film, and this organization should 
be prominent in the presentation. 
The detailed development of every part 
of the film should be slow and clear in 
pictures and words, with primary em- 
phasis on informative picturization. 
The treatment should be consistent 
with the film purpose and should gener- 
ally be expository rather than telling a 
story or hanging on "gimmicks." The 
commentary should be simple, precise, 
brief, direct, dignified and closely inte- 
grated with the pictures. The intro- 
duction should be no longer than 
necessary to take the learners from 
where they are in information to the 
body of the film. The conclusion should 
reinforce the chief learnings. Obviously, 
the project supervisor must lean heavily 
on education and cost experts to make 
sure that he is meeting all his responsi- 
bilities at the script stage. In the same 
way the technical adviser must lean on 
other experts on fine points of the film 
content. 



July 1952 Journal of the SMPTE Vol. 59 



The script and story board must be 
approved by the superiors of both the 
project supervisor and the technical 
adviser. 

Then the project goes into production, 
following the normal procedures of the 
industry. Because emphasis in direct- 
ing, photographing, processing, editing 
and recording is on accomplishing the 
film purpose with integrity and authen- 
ticity, departures from the approved 
master script are never made for reasons 
of caprice, entertainment or aesthetics 
but only when changes are mandatory 
from a teaching point of view. The 
standards set by the industry on the 
technical aspects of photography, proc- 
essing, sound and other film matters 
are followed by the Navy and the 
superiors of the project supervisor care- 
fully check these aspects at interlock 
and acceptance screenings. 

Distribution 

The training aid to meet a specific 
training need has become a reality. 
To move this physical film to the many 
training schools, naval activities, reserve 
schools and the fleet, is a prime re- 
sponsibility of Naval Film Distribution. 
Since the Navy is responsible for the 
production of all motion pictures for 
the Marine Corps, provision is also 
made for distribution to that part of the 
Naval Establishment. Operating under 
the Training Division of the Bureau of 
Naval Personnel, this activity has long 
been aware of the production progress 
of the motion picture. Following the 
Acceptance Screening of the picture 
at NPC, the film is screened before 
specialists at the Bureau of Personnel. 
These personnel have had pre-produc- 
tion information concerning the specific 
need for this particular training aid 
and have had conferences with the 
sponsoring Navy Bureau. The total 
number of film copies needed to perform 
the best training job is ascertained. 
Copies of such a highly specialized film 
as African Trypanosomiasis will not com- 



pare with the need for copies of a film 
on Small Boat Disaster Prevention. Nor- 
mally, each major training film library 
will have at least one copy of every film 
made, and in the majority of instances, 
they will have numerous copies available 
to service the many users. With the 
recall of many reservists and the de- 
mothballing of ships, the major training 
film libraries will have many of the 
hundreds of copies made so that fleet 
units will be able to carry on immediate 
training with these aids. Within a 
month following the Korean outbreak, 
fleet demands swept the shelves of all 
extra copies of training films. Since 
the Navy film program was instituted, 
over 1,300,000 prints of training films 
have been distributed. The training 
potential of these prints is undeniable. 
To answer the question in your minds 
as to actual printing procedures, the 
work is divided between the printing 
facilities at NPC and commercial firms 
awarded printing contracts through 
competitive bidding. 

The Navy feels that its distribution 
program must differ from present-day 
commercial practices. Since a 16mm 
print is relatively inexpensive, the 
emphasis is on making sufficient prints 
of a picture to insure that its information 
can be quickly disseminated, be readily 
available, and in such quantities that 
it will therefore satisfy the original need 
for the training medium. It is not 
unusual for print requirements to exceed 
300 copies before a script is written or a 
camera grinds. 

Procurement 

This last of the three points deals 
with procurement practices of scripts 
and motion pictures not produced 
directly on the NPC sound stage, or by 
NPC crews. 

Last year, over 100 motion pictures 
were completed for the Navy and the 
Marine Corps. Of these, 25% were 
service-produced at or by NPC. The 
remaining 75% were produced com- 



Cronenwett and Timmons: Navy Training Film Production 



53 



mercially under our direct supervision, 
as shown above. 

Almost daily, independent producers, 
large and small, self-styled professional 
cameramen, and small photographic 
facilities want to know whether they 
can make Navy pictures, whether they 
are large enough to produce for the 
Navy, what equipment they must 
buy to produce for the Navy, if the 
Navy will underwrite an initial pro- 
duction, and they ask a thousand other 
questions that might be considered 
laughable, were it not for the seriousness 
of their intent. 

Navy motion pictures have been 
produced commercially by Hollywood's 
biggest firms, and by smaller producers 
in Chicago, Philadelphia, Atlanta, De- 
troit, Pittsburgh, New York, St. Paul and 
elsewhere. 

There are six steps that must be taken 
by a producer wishing to make films for 
the Navy. 

(1) In a letter in triplicate, addressed 
to the Chief, Bureau of Aeronautics 
(PH), Department of the Navy, Wash- 
ington 25, D.C., give a resume of your 
organization, including type and brief 
history, and state whether you are a 
corporation, a partnership, or sole 
proprietor. 

(2) State that you are interested in 
Navy film production and the type you 
consider yourself best suited to handle. 
This information gives the procurement 
officer a better understanding of your 
capabilities and the kind of work on 
which to give you an opportunity to bid. 
If you are one of hundreds on a list, 
it isn't very practicable to ask you to 
bid on a film which will employ highly 
specialized types of medical photog- 
raphy, or other techniques in which 
you are not experienced. If the film 
is to be 100% animation, do you have 
an animation stand? Neither is it 
practicable, if you are located on the 
West Coast, to ask you to bid on a 
submarine film to be shot in New 
London, Conn. 



(3) List your key personnel and give 
a brief outline of their experience in 
motion picture work. 

(4) State the major types of facilities 
and equipment owned, or how made 
available to your company. There are 
no arbitrary rules about the size of your 
studio, nor will the Navy look askance 
at having sound recording done in a 
studio established for that purpose. 
However, if the major portion of your 
equipment is not owned, you are in 
effect not in the motion picture business. 

(5) Enclose a balance sheet listing 
your assets and liabilities. The in- 
formation will be held in strict confidence. 
Give the straight facts. The Navy's 
procurement analysts aren't to be 
fooled. The Navy does not pay in 
advance and the Government cannot 
sponsor you in business. The concern 
is whether you have the capabilities to 
complete an awarded contract. The 
emphasis is upon financial "soundness." 

(6) Forward samples of pictures re- 
cently produced by your company, 
preferably educational or training films. 
The Navy wants to know what you can 
produce now, not what you produced 
several years ago. 

The emphasis is on these basic factors: 

(1) experience (and the kind of experience); 

(2) key personnel and their experience; 

(3) physical facilities in terms of equip- 
ment owned; (4) financial stability: 
(5) the films you have produced and for 
whom; and (6) security clearance. 

There are no geographical advantages, 
except that certain kinds of physical 
work naturally gravitate to the most 
convenient qualified source. But it is 
equally important to note, as all pro- 
ducers would emphatically agree, that 
national assignments involving con- 
siderable distances and location work 
have no such boundaries, that Eastern, 
Midwestern or Western companies work 
over a considerable geographical area. 

The Navy takes considerable pride 
in its past and present procurement 
practices with commercial producers, 



54 



July 1952 Journal of the SMPTE Vol. 59 



large and small. This association has 
been singularly marked by a fine spirit 
of mutual cooperation. 

Conclusion 

This has been a general view of the 
Navy's training film production program. 
It is a big program: 6091 films have 
been produced since the program was 
started back in 1941. It is an important 
program: the films have helped train 
thousands of officers and men. It has 
made at least a small imprint on civilian 
education and training: over 600 titles 
have been released to the public through 
the Office of Education, some of them 
selling as many as 1000 prints. The 
program owes much to the reserve 
officers who got it under way. It also 
owes much to the film industry. We are 
constantly trying to make it better 
not for the sake of being better, but so 
that through training films more men 
can be trained better and faster to do 
jobs that have to be done. 

Supplement 

The Naval Photographic Center's 
film depository and its service to the 
film and television industry are apparent 
to everyone who is familiar with the 
Navy's cooperation and assistance in 
the production of such feature pictures 
as Frogmen, Submarine Command, You're in 
the Navy Now, the television documentary 
serials Crusade in Europe and Crusade in 
the Pacific, and in other current television 
shows and weekly newsreels. The film 
depository at NPC contains over 30 
million feet of historical stock footage 
shot by Navy and Marine cameramen. 
In many instances there is duplicate 
material from other services. Non- 
classified sections of this storehouse of 
film and certain other services are 
available to commercial producers. The 
Navy, with the other services, has ex- 
tended military cooperation or has 
collaborated on the production of com- 
mercial motion pictures for both the- 
atrical and television release. Included 



under cooperation is the search for, 
and use of, official stock motion picture 
footage in connection with commercial 
pictures. 

The clearinghouse for all requests 
for cooperation from any of the services, 
including the use of Navy-owned stock 
footage, is the Commercial Cooperation 
Unit, Pictorial Branch, Office of Public 
Information, Department of Defense. 
The wait for such help is not as long as 
the address mentioned, for the govern- 
ment understands that motion pictures, 
whether full-length features, documen- 
taries or short subjects, and whether 
intended for theatrical or television 
release, are a vitally important and far- 
reaching means of sustaining public 
understanding of the military. The 
Commercial Cooperation Unit is geared 
to get applicants the help they need, 
and coordinates it through the Office 
of the Chief of Information Depart- 
ment of Navy, which handles all further 
details. At this point, NPC enters the 
picture. The time lapse is surprisingly 
short. For instance, a request was 
made and filled within 48 hours for eight 
minutes of stock footage to accompany 
the TV appearance of CDR Gray, 
USN, on the program "We the People." 
The Naval Photographic Center film 
depository will arrange a convenient 
time for you or your representative to 
screen selected stock footage, or if the 
requirement is small will choose the 
material you need and forward it to you. 

It is understandable that the amount 
of cooperation for stock footage or other 
services is directly proportional to the 
reach or scope of the production and 
its potential informational value. Re- 
quests for small lots of stock footage are 
filled as a public service. Either a 
fine -grain or a Kodachrome printing 
master is supplied. In the instances 01 
stock footage for Hollywood major 
productions, arrangements are made to 
reimburse the Navy with a like amount 
of raw stock. 



Cronenwett and Timmons: Navy Training Film Production 



55 



It would be well to mention here that 
an average of 80,000 ft of motion picture 
negative was coming to NPC from 
Navy sources all over the world each 
month before the outbreak of the 
Korean war. Since then, the shipments 
of original unprocessed negative stock 
has risen to 200,000 ft a month. In 
every case where security permits, a 
fine grain of selected footage of timely 
public interest is sent by the Department 
of Defense to the newsreel and television 
pool in New York. Duplicate negatives 
of this timely footage are then purchased 
by production organizations from a 
commercial printing laboratory in that 
area. 

Your initial request for cooperation 
will bring a full set of instructions from 
the Department of Defense. The neces- 
sary, but small details, will not be given 
here. The most important facet of this 
situation is this consideration: if Navy 
footage is required, your production 
will be impracticable or impossible 
without official cooperation from the 
Navy. You will need to furnish a state- 
ment of your intent to produce and 
distribute for public consumption, a 
feature or short subject motion picture 
or television show based on some phase 
of the Navy. Your script will be 
included, and pertinent information as 
to the type of assistance required, i.e., 
stock footage, sound effects, technical 
advice, clearance to board Naval vessels 
or aircraft, or to borrow military 
equipment needed for authentic scenes, 
or actions. 

In any event, security must not be 
compromised, the cooperation must not 
interfere with private enterprise, it 
must not interfere with military opera- 
tions or the command concerned, and 
it must not cost the taxpayer or the 
government anything. An excellent il- 
lustration of such cooperation was the 
recent request by a major Hollywood 
studio wishing to photograph aviation 
activities aboard a carrier. No such 
ship was immediately available for use 



on the West Coast but the camera 
crews were able to board a flattop on 
its way to Korea and do their necessary 
photography before the ship reached 
Hawaii, at which point the commercial 
crews departed. 

Discussion 

M. R. Klein (Director of Army Film Library 
Services) : Does the Navy instructor use a 
teaching technique in using the training 
film prior to showing the film? And also 
as a follow-up after the film is shown? In 
other words, are pertinent questions about 
the film prepared as part of the teaching 
technique in using your film? 

W. R. Cronenwett: If I might comment as 
a former enlisted man, I saw a great many 
training films before I got into my present 
work. The Bureau of Personnel Training 
Division strives in every way to prepare a 
"package," so that the film or other 
visual aid is not the sole teaching medium, 
but exists as one of the teaching tools 
with which the Navy instructor works. 
We have made films for the trained and 
untrained instructor, who then knows 
before he ever meets an audience what 
he should do, how to bone up, the questions 
to ask, what questions he might be asked, 
and the answers. The film, the instruc- 
tor's booklet, the other visual aids, the 
instructor the human element meld 
to train the fleet as best we can. I hope 
I've answered your question. 

Howard Johnson (Federal Civil Defense 
Administration): Referring back to the pro- 
duction aspect of your paper, I think there 
are three points that require re-emphasis 
three significant contributions of the Navy 
training film program. A good many of 
us will agree, I think, that the storyboard 
concept of planning a film is important in 
the documentary training film area; 
secondly, that most training films are one 
reel in length, which is important for 
curriculum integration, important for 
proper film utilization aboard ship or the 
shore station; and thirdly, that most 
Navy training films are documentary 
training films, in the best sense. 

I would like to have you comment 
again on the emphasis of the storyboard 
planning for film production and its value. 

LCDR Cronenwett: We find that in 
working with many people in the Navy 



56 



July 1952 Journal of the SMPTE Vol. 59 



who do not have a film production concept 
that the use of a storyboard, with the 
script, will enable the requesting authority, 
and others who will pass upon the film 
before it gets to the fleet, to visualize the 
final product. As to film length, we feel 
that a film should be designed for a specific 
need. That is, if it needs to be a 3- 
minute film, we'll make it ; if a 1 3-minute 
film, we'll make that too. Too often a 
contract might call for a two-reel picture, 
and when 18^ minutes of film will do an 
adequate job, the film editor will need- 
lessly lengthen the scenes to fill the two- 
reel requirement. 

What was your third point, Mr. Johnson? 

Mr. Johnson: Emphasis on the docu- 
mentary .... 



LCDR Croncnwett: Many of our films, 
as you can well imagine, are documentary 
in approach since many of them are 
photographic reports. In other words, 
we'll go out to cover an amphibious 
landing as best we can, without pre- 
planning, because you can't always know 
what's going to happen. It would be as 
though we had planned to kine the show 
we saw on TV here this afternoon. Some- 
thing invariably happens. May I say 
here, with pardonable pride in behalf of 
those people officer and civilian who 
have made training films for the Navy 
since 1942: twelve Navy films have won 
16 national and international awards. 
I think these awards are based upon 
educationally sound, technically accurate, 
and technically well made motion pictures. 



Cronenwett sin4 Timmons: Navy Training Film Production 



57 



Nonsilver Photographic Processes 



By THOMAS T. HILL 



A number of nonsilver photographic, or light-sensitive systems such as those 
based on diazo dyes, have been used or proposed for specialized purposes. 
None of them, as yet, exhibits the sensitivity or the wide applicability of the 
silver process. This survey of the current status of these systems will discuss 
current limitations as well as possible future prospects with particular reference 
to the field of motion picture engineering. 



D, 



'EFINED BROADLY, photography is 
a very widespread field. It includes 
all those systems by which an image 
can be made more or less permanent, 
an image resulting from an exposure to 
some type of light. Occasionally we see 
mention of new systems of photography 
and though they are often very promis- 
ing, we are still working with the silver 
system of photography. So, the ques- 
tion arises, "Why haven't some of these 
other possibilities come into use?" 

This paper will review some of these 
other possibilities, their advantages and 
their disadvantages in comparison with 
our current silver system, and discuss 
what we are likely to hear from them 
in the near future. 

First, however, we must note that, 
while we grumble about the short- 
comings of the silver emulsions which 
we now use, the necessity of processing 
them in solutions and finally the neces- 
sity of using them properly, they are 



Presented on April 24, 1952, at the Society's 
Convention at Chicago, 111., by Thomas 
T. Hill, The Edwal Laboratories, Inc., 
Ringwood, 111. 



really very versatile and set a high 
mark of accomplishment against which 
to compare the new possibilities. Ex- 
amples of the wide versatility of silver- 
salt photography are easy to find, 
ranging from astronomical photography 
to photomicrography. 

A discussion such as this one develops 
a new respect for the silver system, in 
that it is applicable to so many aspects 
of our work. On examination, we find 
that many of these newer light-sensitive 
systems are of narrow ranges of useful- 
ness. 

Photographic chemistry is but a 
branch of photochemistry, which studies 
all reactions caused by or accelerated 
by exposure to light. Among the many 
photochemical reactions are some which 
appear to be bases of new photographic 
systems, but which on further study are 
either so insensitive or have so limited 
an application that they are not really 
practical. 

Among the possible light-sensitive 
systems of interest to us at present are 
the following (some of these, of course, 
are physical as well as chemical systems) : 



58 



July 1952 Journal of the SMPTE Vol. 59 



diazo dyestuffs; diazo sulfonates; metal- 
diazonium system; dye bleach color 
systems; gelatin dichromate systems 
(and similar ones used in the graphic 
arts); thermography (such as the 
Minnesota Mining system); light-sensi- 
tive glasses (such as those of Corning); 
differentially hardened plastics and resins 
(such as bitumen, etc.); miscellaneous 
metals and metal salts (including those 
of lead, thallium, selenium, etc.); iron 
(such as those in blueprints); electro- 
photography (such as Xerography); 
platinum and palladium compounds 
(actually used in making prints from 
silver-salt negatives) ; and mercury salts. 

Some of these processes or systems 
appeal to us because of either simplified 
processing, adaptability to varied tem- 
peratures, low costs or great stability 
in the final product. But, when bal- 
anced against the advantages of the silver 
process, they have all, up to now, fallen 
short, except for single specialized uses. 

It is that aspect which will be dis- 
cussed here in some detail. We should 
know something of what we can expect 
from these "new" systems and what we 
should not expect from them. In some 
cases, enthusiasm has been substituted 
for results, and we have to use some cau- 
tion in assessing the reported examples 
of new proposals. 

Evaluation of various systems: 

Of course, not all of these nonsilver 
systems are new; many of them have 
been used for years for specific purposes. 
One of the most used is that based on 
the light-sensitivity of iron compounds 
which form a blue-colored salt upon 
exposure to light. We are all familiar 
with the blueprint, and many of us 
have used blueprint paper to make 
prints from still-camera negatives. The 
process, as you will recall, is very slow, 
requiring strong artificial light, or 
sunlight, and in most cases the papers 
in use are designed for high contrast 
rather than for continuous tone repro- 
duction. As generally used, the results 



are not as permanent as silver images, 
although with proper treatment they 
can be made quite satisfactory. 1 But 
such special treatment eliminates two 
of the blueprint's advantages, low cost 
and simple processing. On these bases, 
together with the low sensitivity, we 
can eliminate this system from our 
consideration as a possible competitor 
to a silver compound in actual motion 
picture work. 

In the field of plans and engineering 
drawings, the diazo print 2 is replacing 
the blueprint since it is a positive method, 
giving a positive copy of the original, 
and having greater contrast. Properly 
prepared, it is also more stable. Be- 
cause of its ease and cheapness of 
processing and the low cost of the 
original material, the diazo system of 
photography is more promising than 
many others, and much effort has been 
put into it to make it more useful, and 
more of a competitor to the silver system. 
However, it has some important dis- 
advantages from our present viewpoint, 
mainly very low sensitivity and a limited 
tone range. For black-and-white photog- 
raphy, the diazo system has another 
disadvantage in that there is no true 
dense opaque black available. The 
best blacks, so far, in this field are 
mixtures of dyes giving a very dark 
color which appears black on an opaque- 
base print, but does not have the density 
of a silver material. 

The low sensitivity here is the problem 
which we meet again and again in 
studying the various nonsilver systems. 
In general, the advantage of the silver 
system is that it can be sensitized (in 
the meaning of that word used by 
emulsion chemists). That is, by adding 
small amounts of certain dyes and 
organic compounds together with sulfur 
compounds, the sensitivity of silver 
salts to light, including now the use of 
fluorescent materials, is greatly increased. 
But there is another great difference. 
In silver photography, a latent image 
produced by a very small amount of 



Thomas T. Hill: Nonsilver Photographic Processes 



59 



light is sufficient to give us the final 
results. This is because the working 
image is formed from that insignificant 
latent image by chemical reactions 
which themselves put energy into the 
system. In the case of diazotype, this 
is not the case, and all the energy needed 
to form the image must come from 
light energy. This is, of course, limited 
by the quanta of light available. In 
the case of the diazo system, which is 
a positive process, the light destroys the 
ability of the colorless dye precursor 
to couple to form the colored dye. 
Thus the areas receiving the most light, 
of course, give the least color on develop- 
ment, and those receiving no light 
give the densest color. But the energy 
necessary to make the change which 
produces the image is a result of energy 
applied to the system by the light, 
which makes the exposure. The chemi- 
cal reactions taking place in the coupling 
reaction after exposure do not introduce 
chemical energy in the way that a silver 
photographic developer applies it. 

Diazo materials have been experi- 
mented with as print material for photo- 
graphic uses, 3 and even the simplicity 
of processing has not completely offset 
the low sensitivity and the short tone 
scale. Its success here has been in 
reproducing the sound track used in 
optical methods of sound recording. 4 
Its ability to produce high resolution 
has been given as a great advantage 
here. However, the newer magnetic- 
tape methods of sound recording appear 
to be better at the present state of our 
knowledge. 

As an example of what has been done 
with diazos, one fascinating attempt to 
improve this material, especially in its 
sensitivity, has been that worked out by 
the Philips organization of Holland and 
described in detail in the Journal.* 
Here, the low cost of the diazo material 
and its great resolving power are made 
use of, and the lack of sensitivity is 
partly overcome by combining with 
metal systems of mercury or cadmium, 



and by using silver and other materials 
in the "development." However, tech- 
nical difficulties have yet to be com- 
pletely overcome, and the process has 
not yet been put on the market. We 
will not take time here to discuss it in 
detail since it has already been well 
described in our Journal, as well as in 
other publications. 4 - 5 

A related system is that employing 
the diazo sulfonates, 2 - 6 which differ 
from the diazo system in that they 
produce a negative-type image such as 
we are familiar with from silver salts. 
The other interesting aspect of these 
compounds is that some of them are 
developable by the application of heat, 7 
rather than by chemical reactions of 
separate developers. However, these 
compounds do not appear to be as sensi- 
tive even as the diazo compounds them- 
selves, and there is great difficulty in 
trying to make papers or film materials 
with them which are stable enough to 
store or ship. 

Brief mention should be made here of 
the dye-bleach color systems, 8 such as 
those used in such color photography 
methods as the early types of Caspar 
color and others, which have been 
amply described in our own Journal 
and corollary literature. Here again 
we have the difficulty of sufficient sensi- 
tivity for original taking-film, but the 
materials have been applicable to making 
prints from negatives produced by using 
other processes. 

Of course, several very old systems 
that have been used for reproduction 
purposes are those like the gelatin- 
dichromate 9 system, or its cousins, where- 
in there is a differential hardening of a 
gelatin or other colloidal layer by the 
action of light, which affects the ink- 
receptivity of the layer. 9 * These systems 
are the mainstay of the printing trades 
today and they are exceedingly useful 
in many ways, but they have a low 
sensitivity and require arc-light expo- 
sures, as well as freshly coated material 
prepared just before exposure. Recent 



60 



July 1952 Journal of the SMPTE Vol.59 



attempts have been made, some success- 
fully, to utilize diazo-type compounds 
in printing-plate materials 10 in order 
to obtain presensitized plates which 
can be prepared and stored for some 
time before use. These still, however, 
require strong light sources and long 
exposures. All these systems require 
the use of a "screen" in order to re- 
produce tones, which limits their use- 
fulness. 

In somewhat the same field, fall the 
various differentially hardened plastics 
and resins, 11 and the old methods 
utilizing such materials as bitumen and 
pitch. As a matter of fact, some of the 
very old photographic processes antedat- 
ing the daguerreotype utilized such 
systems 12 ; however, they required ex- 
posures to sunlight in terms of hours, 
and did not give a very stable result. 

An interesting variation of this idea 
is a recent report from a German ex- 
perimenter 13 of the fact that the use of a 
tanning developer such as catechol, on 
a silver halide emulsion in gelatin will 
produce shadow detail in the gelatin 
itself in areas beyond those which 
receive the weakest silver image upon 
development. It is proposed to make 
use of this by dying the gelatin and 
then washing away the unhardened 
lesser-exposed areas with warm water, 
leaving a silver image, together with 
this dye-plus-gelatin image, which com- 
bines to make a denser negative, espe- 
cially in the very weak shadow regions. 
This would, of course, require a special 
type of emulsion and additional special 
treatment which, though it appears to 
be capable of greater sensitivity than 
the silver methods normally used, re- 
quires extra care and treatment in 
processing which makes it difficult of 
application. 

Salts of various heavy metals such as 
lead, 14 thallium, 15 selenium 16 and many 
others have been used to form photo- 
graphic images, such as were also 
formed in an experiment during the 
late war by one military man who used 



the familiar trinitrotoluene or TNT 
to make a photographic image. 17 He 
did this by coating paper with a solution 
of TNT, drying it and exposing it to 
light. In all these cases the sensitivity 
so far appears to be very low, and no 
method of increasing the sensitivity has 
yet been reported. 

One rather surprising nonsilver sys- 
tem has recently been proposed which 
is brought to mind by the use just 
mentioned for TNT. This is the use 
of explosive materials to form an image 
by the results of the explosion. In a 
recent report the use of nitrogen tri- 
iodide is described. This is a ticklish 
material which many of us used to use 
in schooldays for practical jokes; it 
will explode with great noise when 
slightly disturbed, even when tickled 
with a feather. In this case, the light 
falling on it through a lens is sufficient 
to set off an explosion, and an image 
is left on the support, burned in by the 
explosion. 18 

The light-sensitive glasses developed 
by the Corning Glass Works 19 are of 
interest, especially as they will give 
some colors as well as black-and-white 
images, but they are not practical for 
motion picture engineering use because 
of the fragility of the base material, 
the special processing (requiring very 
high temperature fusing) and other 
difficulties, which we understand also 
include a low sensitivity. The colors 
obtained are not "natural" colors as in 
Kodachrome, etc. 

On the other hand, quite interesting 
advances have been made with various 
processes of electro-photography, such 
as have been developed at the Battelle 
Memorial Institute in connection with 
the work of Haloid Go. under the name 
of Xerography. 20 Further work on this 
has been done at the Signal Corps 
Engineering Laboratories (Squier Signal 
Corps Laboratory) at Fort Monmouth, 
N. J., and reported in the recent litera- 
ture. 21 They appear to have overcome 
the early difficulties of poor tone-scale 



Thomas T. Hill: Nonsilver Photographic Processes 



61 



reproduction, and we have seen portraits 
made by this process which had fairly 
good quality. 

The process basically involves the 
"sensitizing" of a prepared selenium 
plate by giving it an electrostatic charge. 
Upon exposure to light, in our case to 
an image, the resistance of the plate 
drops in the higher exposure regions, 
so that the charge there is less. De- 
velopment consists of dusting on a dry 
powder which clings to the areas still 
holding the most electrostatic charge. 
This powder image may be fused to 
permanence by heat, or transferred to 
another paper support and then fused. 
Three to five seconds in a photographic 
dry mounting press will do the trick. 
The plate itself can then be cleaned and 
re-used for another picture. The great 
advantage here is the speed of processing 
and the fact that it is an all-dry system 
without water solutions. However, the 
manipulation by the operator including 
the preparation of the plate just before 
exposure, whether of selenium or of 
phosphors 22 (both of which systems are 
used), is quite difficult and delicate, 
and a high-tension electrical system is 
necessary to utilize this method. It 
gives a direct-positive result, and does 
not as yet appear to be applicable to a 
negative-to-positive system. However, 
a great deal of work is being done on 
it for the various applications such as 
photocopy work, special Air Corps 
cameras, and even for X-ray use, 23 and 
to prepare lithographic printing plates. 24 

Another interesting process announced 
fairly recently, is that referred to as 
thermography, 26 exemplified by the heat 
copying process, recently announced by 
the Minnesota Mining & Mfg. Co. In 
this process, called Thermofax, the 
image is formed by an infrared or heat 
exposure which melts a waxy material 
where inked areas concentrate the heat, 
and the resulting image on a special 
paper is both a positive and a negative. 
This may be rather confusing, but the 
fact is that as a result of this exposure 



you get a print on a semi-opaque paper 
which by reflected light looks like a 
positive, since the exposed areas are 
darker than the chalky blue-white 
background (of the example we saw). 
However, when viewed by transmitted 
light, those exposed areas become a 
transparent light blue against an opaque 
whitish-blue background, and form a 
negative image which can be used to 
make prints by usual contact printing 
methods on silver-salt materials. This 
appears to have interesting applications 
for office photocopy use, and this is the 
first commercial application being 
worked on. However, it requires ex- 
posure to heat, or infrared rather than 
visible light rays. It does not appear 
to have a great deal of tone range, and 
it appears to be very slow, as with so 
many of these nonsilver systems; there- 
fore, as presently described, it does not 
appear to have any application at all 
for our present purposes. 

Conclusions 

Having now discussed and described 
some of these proposed light-sensitive 
systems, the question is, Where do we 
go from here? 

It would seem that each of these 
systems, which we have so briefly 
examined, has at least one great short- 
coming in comparison to the silver- 
salt process we are so familiar with. 
They all appear to have a low sensi- 
tivity to light. Many of them appear 
to have a poor tone range, and some of 
them seem to require even more compli- 
cated processing techniques to produce 
the final image. 

It would therefore seem that, as pre- 
sently developed, none of these systems 
has any immediate direct application to 
motion picture photography, that is in 
preparing either the positive print or 
the negative film from which the positive 
is printed. There are a few cases, such 
as the Philips diazonium system, which 
appear to have some promise for 
making prints. This is also true of 



62 



July 1952 Journal of the SMPTE Vol. 59 



some of the dye-bleach color systems 
such as early Caspar color. In a few 
cases the low sensitivity is not so im- 
portant. But where the sensitivity has 
been even somewhat increased, the cost 
of the material is no longer low, and 
therefore such a system is less competitive 
with the silver-salt process than it was 
originally. 

Of course, in auxiliary aspects of our 
work, some of the nonsilver processes 
can be used but not in a direct, motion- 
picture-taking application. 

But what of the future? Can some 
of these processes come up to the overall 
advantages of the silver process? A 
close study of the literature in a number 
of these cases, and first-hand experience 
with a number of these processes in the 
laboratory, indicate that they have 
a long way to go before any of them 
could successfully challenge silver for 
more than a small part of silver's great 
range of usefulness. For example, we 
have had an opportunity to watch an 
investigation recently of claims to a new 
process by which the sensitivity of a 
diazo dye process was to be increased 
to equal that of silver materials. When 
it was finally boiled down it was found 
that the sensitization simply did not 
work. Applied to textiles, this special 
type of diazo process was quite practical, 
but it required terrifically long ex- 
posures or exposures to extremely bright 
light at very close range, and it required 
exposure of the material while wet. So, 
another hopeful method of speeding up 
one of the nonsilver processes went by 
the board. 

In general, our present conclusion 
must be that none of these other proc- 
esses is likely to become competitive 
to the silver process in the near future, 
for our purposes. In some specialized 
fields, such as photocopy work, and other 
cases where high exposure speed and 
good tone range are not necessary, there 
is great hope that some of these methods 
will give results equal to that given by 
silver emulsions at lower costs and with 



simpler processing techniques, but with 
the very high requirements of the motion 
picture art, we of this group cannot 
expect much from any of these "new" 
systems for a long time to come. 

Therefore our major efforts at present 
should be expended on improving the 
processing technique of the silver process 
in order to simplify it, and lower the 
cost. Some of these methods appear 
to be very promising, such as the 
stabilization techniques to replace the 
fixing and washing stages of normal 
silver processing. The use of higher 
temperatures, spray processing pro- 
cedures and other improvements in 
this aspect, will decrease some of the 
few disadvantages of our familiar and 
very successful silver light-sensitive 
process. 
Bibliography 

D. A. Spencer, Ed., Progress in Photography, 
1940-1950, Focal Press, London and 
New York, 1951. 

M. M. Eder, History of Photography, trans- 
lated by E. Epstean, Columbia Uni- 
versity Press, New York, 1945. 
K. H. Saunders, The Aromatic Diazo Com- 
pounds and Their Technical Applications, 
2nd ed., Edw. Arnold & Co., London, 
1949. 

J. Friedman, History of Color Photog- 
raphy, American Photographic Pub- 
lishing Co., Boston, 1942; and his 
monthly columns in American Pho- 
tography in the 1930's and 1940's. 
Edward K. Kaprelian, "A survey of 
photographic processes and materials," 
Phot. Eng., 7, No. 2: 42-55. (This 
includes an extensive bibliography of 
80 items.) 

J. W. Mitchell, Ed., Fundamental Mecha- 
nisms of Photographic Sensitivity, Butter- 
worth's, London, 1951. 
B. de Goster, "The principles and possi- 
bilities of diazo-copying processes," /. 
Documentation, 5: 1-11, June 1949. 
S. C. Slifkin, "Status of developments in 
the German diazotype reproduction 
process," FIAT final Report No. 1082, 
May 2, 1947; PB Report No. 78,256. 
(These are published by agencies of 
the U.S. Dept. of Commerce, Wash- 
ington 25, B.C.) 



Thomas T. Hill: Nonsilver Photographic Processes 



References 

1. C. A. Crowley and J. B. Mullen, 
U.S. Pat. 2,317,521. 

2. K. H. Saunders, The Aromatic Diazo 
Compounds and Their Technical Applica- 
tion, 2nd ed., Edw. Arnold & Co., 
London, 1949, pp. 363 ff. 

3. A. M. Gheftel, "Ozaphane film and 
the Cinelux projector," Jour. SMPE, 
25: 358-360, Oct. 1935; A. M. 
Sookne and C. G. Weber, "The 
stability of the viscose type of ozaphane 
photographic film," Jour. SMPE, 31: 
611-618, Dec. 1938. 

4. R. J. H. Alink, G. J. Dippel and K. J. 
Keuning, "The metal diazonium sys- 
tem for photographic reproductions," 
Jour. SMPTE, 54: 345-366, Mar. 
1950. (This article was reprinted 
from Philips Technical Rev., 9: 289-300, 
1948.) 

5. C. J. Dippel, "The metal diazonium 
process," Phot. J., 90B: 34-41, Mar.- 
Apr. 1950. 

6. FIAT Final Reports, Nos. 528 and 
813 (available from the U.S. Dept. 
of Commerce, Office of Technical 
Services, Washington 25, D.C.) and 
BIOS Final Report No. 1480, p. 72 
(available from British Information 
Services, 30 Rockefeller Plaza, New 
York 20, N.Y.). 

7. FIAT Final Report No. 528, p. 6. 

8. J. Friedman, History of Color Photog- 
raphy, American Photographic Pub- 
lishing Co., Boston, 1942, p. 502; 
B. Caspar, U.S. Pat. 2,049,005; E. I. 
DuPont de Nemours & Co., Brit. Pat. 
592,679 (U.S.A., May 9, 1944). 

9. (a) C. M. Willy, Practical Photolithog- 
raphy, Pitman, London, 1940, es- 
pecially pp. 1-3; (b) J. S. Mertle, 
Process Photography and Platemaking, 
G. Cramer Dry Plate Co., St. Louis, 
Mo., 1946, especially pp. 133-137. 

10. Robert C. Rossell, "Hi-speed process- 
ing plate," NatL Lithographer, 56, No. 
5: 40, 60, May 1949. 

11. R. E. Liesgang, Z. wiss. Phot., 30: 
156-157, 1931. 

12. J. M. Eder, History of Photography, 1st 
English translation by E. Epstean, 
Columbia University Press, 1945, pp. 
200 ff. 

13. J. Rzymkowski, "A Method of In- 
creasing Photographic Sensitivity by 



Tanning Development," in Funda- 
mental Mechanics of Photographic Sensi- 
tivity, J. W. Mitchell, Ed., Butter- 
worth's, London, 1951, p. 220. 

14. A. Schoen, General Aniline & Film, 
U.S. Pat. 2,414,839 and 2,504,593. 

15. M. J. Harper and M. Ritchie, "Further 
observations on latent image formation 
in thallous bromide gelatin systems," 
Trans. Faraday Soc., 46: 641-645, Aug. 
1950. 

16. P. Selenyi, "Photography on se- 
lenium," Nature, 767: 522, Apr. 1948; 
also, G. Berraz and E. Virasaro, 
Anales inst. invest, dent, y tecnol. (Univ. 
nac. litoral, Santa Fe, Arg.}, 10/11, No. 
17: 41-47, 1942. 

17. W. Snelling, Plum Brook Ordnance 
Works News, 1, No. 20: 1, 6, Nov. 1942. 

18. J. Eggert, "Contribution to the Photo- 
chemistry of Endothermic Com- 
pounds," in Fundamental Mechanics of 
Photographic Sensitivity, J. W. Mitchell, 
Ed., Butter worth's, London, 1951, 
pp. 220 ff. 

19. R. Dalton, U.S. Pat. 2,326,012, 1943; 
and 2,422,472, 1947; S. D. Stookey, 
"Photosensitive glass, new photo- 
graphic medium," Ind. Eng. Chem., 
41, No. 4: 856-861, Apr. 1949; W. H. 
Armistead, Jr., and S. D. Stookey, 
Canadian Pat. 442,272; 442,273; 
and 442,274, Dec. 8, 1943. 

20. C. F. Carlson, U.S. Pat. 2,221,776, 
1940; 2,277,103, 1942; 2,297,691, 
1942; and 2,357,809, 1944. See 
also review of patents in this field by 
Frank Smith, Phot. Eng., 2, No. 4: 
258-259, 1951. 

21. See review of patents in this field by 
Frank Smith, Phot. Eng., 2, No. 4: 
258-259, 1951. 

22. R. E. Aitchison, "Preparation of 
photoconducting cadmium sulphide," 
Nature, 167, No. 4255: 812-813, May 
1951; also E. Wainer, "Phosphor 
type photoconductive coatings for con- 
tinuous tone electrostatic electrophotog- 
raphy," Phot. Eng., 3, No. 1: 12-22, 
1952. 

23. R. C. McMaster, "New developments 
in Xeroradiography," Non-Destr. Test- 
ing, 10, No. 1: 8-25, Summer 1951. 

24. L. E. Walkup, "Lithographic plates by 
Xerography," Penrose Annual, 45: 134- 
135, 1951. 



July 1952 Journal of the SMPTE Vol. 59 



25. F. CJrbach, "Thermography," Phot. 
J., 90S, No. 4: 109-114, July 1950; 
Thermojax, leaflet published by Minne- 
sota Mining & Mfg. Co., St. Paul, 
Minn. 

Discussion 

Wm. H. Ojfenhauser (Consultant): In 
among some old film clips that I had a 
number of years ago, there was a strip of 
diazo process film that was printed in 
France. The picture was Dreyfus. I lost 
its history from that point on. I wonder 
if you can tell us why the thing died or 
why it might have started at all. 

Thomas T. Hill: There was a lot of 
promise in that process. Of course, the 
diazo system is promising because you 
have colors there and they thought they 
could make use of it. Also it's nongelatin. 
Actually the sensitive material is cast 
right into the base, whether it's a celluloid 
base or a cellophane base. Most of the 
sound-track methods were on a cellophane 
base like the Philips diazonium process. 
One of the drawbacks was that you did 
not have the dimensional stability and 
the overall usefulness of your prints 
running as many hundreds or thousands of 
times as does a good print from material 
we use now. 

Another trouble was that these diazo 
dyes were not as light stable, and after 
projection a few dozen times the image 
began to fade. It's very difficult to get 
good fixing with diazo materials so 
nothing intensifies or darkens, and so that 
the dyes do not fade. That seems to be 
why that thing has fallen by the wayside 
up to now. There's still enough promise, 
I think, to continue with it, but it isn't as 
good as was hoped for in the beginning. 

Anon: Is there anything in the literature 
that would indicate the problems of sound 
recording on these nonsilver media? 

Mr. Hill: That was one of the applica- 
tions that the Philips diazonium process 
was aimed at, because of its terrifically 
high resolution they thought they could 
get a better sound track. But when I 
talked to the men who had worked on it 
in this country they told me that they 
had found several things wrong with the 
thing as developed in Holland and sent 
it back for further research. One of the 
troubles was that they spent all of their 
time working on a material on a cello- 



phane base. Because of the very thinness of 
the material they could put a big reel of 
film with sound track on a very small 
area, but the people in this country 
pointed out that the dimensional stability 
of the cellophane wasn't up to what we're 
used to in the motion picture industry 
and it just simply wouldn't work for that 
reason. 

The other thing was, of course, the 
mercury involved a health hazard which 
they apparently hadn't realized. So it 
has gone back to Holland for work with 
the cadmium aspect of the system and Dr. 
Jamieson of the Philips Laboratories in 
Irvington-on-Hudson, New York, told 
me recently that there's some promise 
that they'll come back again with better 
results for that specific purpose on sound 
track. 

Anon: So the summary is probably that 
Eastman Kodak and du Pont and Ansco 
can continue to make film for a little while? 

Mr. Hill: For quite a while. 

Anon: Until the magnetic boys catch 
up with them. 

Mr. Offenhauser: I'd like to bring in a 
little more history at this point. Just 
before World War II when I was with 
John Maurer we were working with a 
wide-range silver film master record 
recording system for frequency modulation 
broadcasting. We used Class A push- 
pull, direct-positive recording on yellow- 
dyed silver film with galvanometers that 
peaked at 22 kc and with a film speed of 
60 ft per min. The direct-positive was 
printed in diazo material by Agfa-Ansco 
at Binghamton. 

We made prints on diazo material and 
the objective at that time was to use the 
prints from these records for FM stations 
as transcription record material on account 
of the fact that we found very low distortion 
levels in the diazo prints from the silver 
originals. I mention this as a matter of 
history. 

Mauro ^ambuto (Scalera Films, Rome, 
Italy): One advantage of those diazo films 
was that they scratched less in some aspects 
of them. In connection with the sound- 
track use of the diazo materials, I wish to 
say that I also had some experience with 
that particular film that was made in 
France, and incidentally it was Dreyfus. 
That was back in 1939. Now, there was 
one major problem at the time due to the 



Thomas T. Hill; Npnsilver Photographic Processes 



65 



fact that the diazo materials never seemed 
to reach a very high density. So in this 
particular instance, the most trouble they 
had was with the signal-to-noise ratio. I 
would like to know if in the new experi- 
ments anything better has been achieved. 

Mr. Hill: There has been a good deal 
of work done on that aspect simply for 
the office copying use of diazo on paper 
in trying to get a better and more opaque 
black, and I'm sure that some of those 
things have given us combinations of dyes 
which are better than we had, say, twelve 
or thirteen years ago. It is that total 
density that they're trying to improve, 
but as with any of the dyes, where you have 
a black dyestuff for cloth or any other 
purpose, you really have a very dark color 
rather than a true black. In the same way 
with the diazo coupling, and as I mentioned 
before, there is a faint fading going on so 
that when you've got a total density 
that's still a little less than you want and 
then it starts to fade, you've still got 
trouble. But I'm sure that some of the 
dyes that have been worked out in the 



past four or five years are much better 
than they've had before. 

Mr. Zjambuto: Could you give us any 
figure as to the amount of signal-to-noise 
ratio that was achieved? 

Mr. Hill: In that case I can't. The 
stuff I have seen has been on paper ma- 
terials. We've been involved in the basic 
chemicals rather than in the application, 
so that we don't have that part of it going 
through our lab. But we do have the 
basic chemicals and their coupling to get 
a black, black as possible on paper. 

Mr. Offenhauser: As I remember it, we 
had something like 60-db signal-to-noise 
ratio and something less than 2% harmonic 
distortion. The figures can be obtained, 
I believe, from Andre Schoen in Bing- 
hamton; he has the logs and test data. 
We would never have contemplated using 
these materials for FM transmission unless 
the performance was that good or better. 
We used blue-sensitive photocells with 
matching dyes; these latter were peaked 
in the same general spectral range. We 
tried many dyes and cells experimentally; 
the blue combination proved to have the 
best performance at the time. 



66 



July 1952 Journal of the SMPTE Vol. 59 



72d Semiannual Convention 



Hotel Statler, Washington, D.C. 
October 6-10 

Wheels have been turning for the 
Washington Convention ever since the 
Editorial-Papers Committee Meeting at 
Hollywood last October. In addition 
to specific plans for last April's Chicago 
Convention, general plans were laid for a 
year ahead and Joe Aiken, Papers Com- 
mittee Vice-Chairman for Washington, 
D.C., was welcomed and was promised 
cooperation from all present in his job as 
Program Chairman. 

The 72d Convention, even in its present, 
embryonic form, is proving again the worth 
of the practices and procedure worked out 
over the past few years by Papers Com- 
mittee Chairman Ed Seeley. It used to 
be that the Papers Committee Chairman 
organized the technical papers program 
on his own primary responsibility and also 
almost completely by his own efforts. 
Not only was this a great burden on the 
same individual twice a year but also it 
was apparently less effective than having 
someone in the convention city responsible 
for the program; so Ed Seeley set up the 
title and function of Program Chairman. 
The Program Chairman is the Papers 
Committee Vice-Chairman in the con- 
vention city. General advice and carry- 
over information go to the Program 
Chairman from the Papers Committee 
Chairman and also from the Program 
Chairman of the previous convention. 
The Society's headquarter's staff assists 
only by trying to assure mutual under- 
standing by all concerned and by channel- 
ing suggestions which come from divers 



members. The Editorial Vice-President 
is responsible to the Society's Board of 
Governors for the function of the Papers 
Committee and so, also, for the technical 
sessions of conventions. The Editorial 
Vice-President's convention role, as most 
recently exemplified by John Frayne, is 
that of being helpful only when called upon 
specifically and by using his special and 
good offices to obtain special papers or 
initiate plans for particular sessions. 

Leads, suggestions, or finished papers 
may originate with any interested person 
but all paper possibilities should be chan- 
neled through a Papers Committee mem- 
ber. The Papers Committee Vice-Chair- 
man in the area should be kept informed 
of the development. Papers Committee 
members and vice-chairmen are responsible 
for initiative in their respective companies 
or areas. 

For the Washington Convention, Joe 
Aiken will also be Local Arrangements 
Chairman, assisted by a roster of Wash- 
ington folks who were nearly all appointed 
at a meeting in Washington on May 29 
when Convention Vice-President Bill 
Kunzmann was in Washington to make 
convention plans and commitments. The 
list of those responsible for the many 
duties and functions will be published in 
the August Journal but this does not 
mean that there is no room for more 
helpers or suggestions, particularly for 
research, techniques or new products 
manuscripts. These should preferably be 
channeled through the Papers Committee 
Vice-Chairman or member nearest you. 
The complete Papers Committee is: 



PAPERS COMMITTEE 

Chairman: Edward S. Seeley, Altec Service, 161 Sixth Ave., New York 13 

72d Convention Program Chairman: J. E. Aiken, 116 N. Galveston St., Arlington, Va. 

Vice-Chairmen 

For New York: W. H. Rivers, Eastman Kodak Co., 342 Madison Ave., New York 17 

For Chicago: Geo. W. Colburn, 164 N. Wacker Dr., Chicago 6, 111. 

For Los Angeles: F. G. Albin, Station KECA-TV, American Broadcasting Company 

Television Center, Hollywood 27, Calif. 

For Canada: G. G. Graham, National Film Board of Canada, John St., Ottawa, Canada 
For International Symposium on High-Speed Photography: John H. Waddell, 850 Hudson St 

Rochester 4, N.Y. 



67 



Papers Committee Members 

D. Max Beard, Naval Ordnance Labora- 
tory, White Oak, Silver Spring, Md. 

A. C. Blaney, RCA Victor Div., 1560 N. 
Vine St., Hollywood 28, Calif. 

Richard Blount, General Electric Co., 
Nela Park, Cleveland, Ohio 

R. P. Burns, Balaban & Katz, Great 
States Theaters, 177 N. State St., 
Chicago 1, 111. 

Philip Caldwell, American Broadcasting 
Co., 6285 Sunset Blvd., Hollywood, 
Calif. 

F. O. Calvin, The Calvin Co., 1105 E. 
Fifteenth St., Kansas City 6, Mo. 

J. P. Corcoran, Twentieth Century-Fox 
Film Corp., 10201 W. Pico Blvd., 
Beverly Hills, Calif. 

P. M. Cowett, Dept. of the Navy, Bureau 
of Ships, Washington 25, D.C. 

G. R. Crane, Westrex Corp., 6601 Ro- 
maine St., Hollywood 38, Calif. 

E. W. D'Arcy, De Vry Corp., 1111 W. 
Armitage Ave., Chicago 14, 111. 

W. P. Button, 732 N. Edison St., Arlington 

3, Va. 
Farciot Edouart, Paramount Pictures 

Corp., 5451 Marathon St., Hollywood 

38, Calif. 

F. L. Eich, Paramount Film Laboratory, 
1546 Argyle Ave., Hollywood 28, Calif. 

Charles Handley, National Carbon Div., 
841 E. Fourth PI., Los Angeles 13, Calif. 

R. N. Harmon, Westinghouse Radio Sta- 
tions, Inc., 1625 K St., N.W., Washing- 
ton, D.C. 

Scott Helt, Allen B. Du Mont Labs., Inc., 
2 Main Ave., Passaic, NJ. 

C. E. Heppberger, National Carbon Div., 
230 N. Michigan Ave., Chicago 1, 111. 

J. K. Hilliard, Altec Lansing Corp., 1161 
N. Vine St., Hollywood 38, Calif. 

L. Hughes, Hughes Sound Films, 21 S. 
Downing St., Denver, Colo. 

P. A. Jacobson, University of Washington, 
Seattle, Wash. 

William Kelley, Motion Picture Research 
Council, 1421 N. Western Ave., Holly- 
wood 27, Calif. 



George Lewin, Signal Corps Photographic 
Center, 25-11 35 St., Long Island City 
1, N.Y. 

E. C. Manderfeld, Mitchell Camera Corp., 
666 W. Harvard St., Glendale 4, Calif. 

Glenn Matthews, Research Laboratory, 
Eastman Kodak Co., Rochester 10, N.Y. 

Pierre Mertz, Bell Telephone Labs., Inc., 
463 West St., New York 14 

Harry Milholland, Allen B. Du Mont 
Labs, Inc., 515 Madison Ave., New 
York 22 

W. J. Morlock, General Electric Co., 
Electronics Park, Syracuse, N.Y. 

Herbert Pangborn, Columbia Broadcast- 
ing System, Inc., 6121 Sunset Blvd., 
Hollywood 28, Calif. 

B. D. Plakun, General Precision Labora- 
tory, Inc., Pleasantville, N.Y. 

Edward Schmidt, Reeves Soundcraft, 10 
E. 52 St., New York 22 

N. L. Simmons, Eastman Kodak Co., 
6706 Santa Monica Blvd., Hollywood 
38, Calif. 

S. P. Solow, Consolidated Film Industries, 
Inc., 959 Seward St., Hollywood 38, 
Calif. 

J. G. Stott, Du-Art Film Laboratories, 
245 W. 55 St., New York 19 

W. L. Tesch, Radio Corporation of 
America, RCA Victor Div., Front and 
Cooper Sts., Camden, N.J. 

S. R. Todd, Consulting Electrical Engi- 
neer, 4711 Woodlawn Ave., Chicago, 111. 

M. G. Townsley, Bell & Howell, 7100 
McCormick Rd., Chicago 45, 111. 

Three special sessions have long been 
scheduled for the Washington Convention: 
(1) an international symposium on high- 
speed photography for as much as two full 
days' sessions, some or all of them con- 
current with other sessions; (2) a session 
on magnetic striping of film; and (3) a 
session on maintenance of 16mm equip- 
ment. More details about these and other 
sessions will be given in next month's 
Journal. On August 6 all members will 
be sent the Advance Notice of the Con- 
vention. This is the usual folded postal 
mailer which gives the schedule of sessions 
and includes a tear-off postal for making 
hotel reservations. 



68 



Engineering Activities 



Status of Proposed Standards: In the past year or so quite a few proposed standards have 
been published for trial and criticism. The status of these is outlined below to bring all 
concerned up to date. Henry Kogel, Staff Engineer. 



Title 



PH 

22 



Date 
pub. 



Status 



Cutting and Perforating Dimensions 
for 35mm Motion Picture Film 
Alternate Standards for Either Posi- 
tive or Negative Raw Stock 

Emulsion and Sound Record Positions 
in Camera for 1 6mm Sound Motion 
Picture Film 

Emulsion and Sound Record Positions 
in Projector for Direct Front Pro- 
jection of 16mm Sound Motion 
Picture Film 

Screen Brightness for 35mm Motion 
Picture 

A & B Windings of 16mm Raw Stock 
Film with Perforations Along One 
Edge 



1 9/51 Approved by Standards Com- 

mittee. Now out to letter 
ballot of ASA Sectional 
Committee PH22. 

15 12/511 Further revisions have been 

i proposed which are now 
being considered by the 

16 12/51] 16 and 8mm Committee. 



.39 



,75 



5/52 



1/51 



Edge Number 16mm Motion Picture .83 1/51 



Dimensions for Projection Lamps .84 2/51 

Medium Prefocus Ring Double- 
Contact Base-Up Type for 16mm 

and 8mm Motion Picture Projectors 
Dimensions for Projection Lamps .85 2/51 

Medium Prefocus Base-Down Type 

for 16mm and 8mm Motion Picture 

Projectors 
Enlargement Ratio for 16mm to .92 1/52 

35mm Optical Printing 



Trial period ends Aug. 15. 
No Adverse comments re- 
ceived as yet. 

Adverse comments were re- 
ceived. Several new drafts 
have since been proposed 
by 16 and 8mm Committee 
to resolve the differences. 
The latest is now going out 
to letter ballot of the 16 and 
8mm Committee. 

Approved by PH22. Must 
next be reviewed by 
SMPTE Board of Gover- 
nors for Sponsor approval. 



Approved by Standards Com- 
mittee. Now out to letter 
ballot of ASA Sectional 
Committee PH22. 



SMPTE Officers and Committees: The roster of Society Officers and the 
Committee Chairmen and Members were published in the April Journal. 



69 



Letters to the Editor 



Re: Three-Dimensional Motion Picture Nomenclature 



I have read with great interest Major 
Bernier's article on "Three-Dimensional 
Applications" which appeared in the 
Jour. SMPTE, 56: 599-612, June 1951. 

Major Bernier is to be congratulated on 
his paper and also on the interesting ex- 
perimental work which he and his unit 
are conducting. The writer would, never- 
theless, like to draw attention to a few 
points in the paper in connection with 
which there seems to be some confusion. 

On page 599 in the Journal, reference is 
made to "the composite or lenticulated 
system," but just what Major Bernier is 
endeavoring to convey by this terminology 
is not clear. There are three main groups 
of processes (embracing hundreds of 
different modes of application) which 
might conceivably, but should not, be 
referred to in this way. These three groups 
comprise: (1) integral processes, which 
had their genesis in the idea conceived by 
Gabriel Lippman and disclosed by him 
in 1908 (Compt. rend., 746: 446-51); (2) 
parallax stereogram processes, all of which 
are derived from the principle described 
in Frederic Ive's U.S. Pat. 725,567 (ap- 
plication date, Sept. 25, 1902); and (3) 
parallax panoramagram processes, which 
depend on the principle of G. W. Kanolt, 
described by him in his U.S. Pat. 1,260,682 
(application date, Jan. 16, 1915). 

The problems involved in producing 
spherically lenticulated film as proposed 
by Lippman were not solved during the 
inventor's lifetime, but the earliest practical 
process (for still photography) employing 
a cylindrically lenticulated screen with 
which the writer is acquainted was de- 
scribed by Walter Hess in 1911 in his 
Brit. Pat. 13,034. 

The most important of Dr. Herbert 
Ive's ideas relating to stereo kinematog- 
raphy are those embodied in Brit. Pat. 
348,118 (application date, Feb. 7, 1930) 
and his corresponding U.S. application 
(convention date, Feb. 9, 1929). Very 
many other processes involving the use 
of line or lenticular grids, for both still 
and motion pictures, were evolved be- 
tween 1911 and 1929. 



In discussing, on page 601 of the Journal, 
the various factors contributing to depth I 
perception, Major Bernier has again 
departed from accepted terminology, and 
this may be confusing to some with limited 
knowledge of the subject. For example, 
factor No. 4, in Major Bernier's list should 
read "Accommodation," not "Focus re- 
action," and factor No. 6 should read 
"Binocular vision," not "Stereoscopic 
vision." 

The word "stereoscopic" means (freely 
translated from the Greek), of course, 
"seeing solid" or, as we are accustomed 
to say, three-dimensionally or stereoscopi- 
cally. Accordingly, the term "stereoscopic 
vision" applies to the net effect resulting 
from the various contributory factors. In 
compiling a "short list" of these factors, 
it is, in the writer's opinion, difficult to 
improve on the custom of dividing them 
into two groups: (1) monocular factors; 
and (2) binocular factors. In the first 
group the chief factors are accommodation 
and perspective, and in the second group 
we have parallax and the faculty of con- 
vergence. There are numerous subsidiary 
factors, some of which are mentioned by 
Major Bernier. 

Referring to the comments in the second 
paragraph of page 601, whilst it is, of 
course, true that accommodation becomes 
of decreasing importance with increasing 
distance of the object, neither this fact 
nor any other warrants definition of a 
distance of 20 ft as "optical infinity." 

The reasoning on the next paragraph 
of the paper is based on a fallacy. It can 
best be demonstrated experimentally that 
the faculty of accommodation is stimulated 
practically always when one is watching 
projected motion pictures. The apparent 
size of the image is no less important than 
the distance of the screen in determining 
the degree of stimulation. Let us suppose, 
for example, that the film being projected 
depicts an object moving toward or away 
from the observer so that it is progressively 
either increasing or decreasing in size. 
If the object depicted is a familiar one, 
and the apparent size of the image corre- 



70 



spends to a distance within the normal 
range of accommodation, the eye will 
attempt to accommodate for that distance. 
This momentarily throws the screen out 
of focus, so the eye then re-accommodates 
\ for the plane of the screen. If, by that 
time the image of the object assumed 
to be still moving is at a different 
"apparent" distance within the range of 
accommodation, the eye will attempt to 
accommodate for the new distance, there- 
by again throwing the screen out of focus. 
This cycle of events recurs with great 
rapidity, and is sometimes the cause of 
headaches amongst elderly cinema patrons, 
whose ocular sensory organs and muscles 
are, naturally, less responsive than those 
of younger people. 

With regard to the main subject dis- 
cussed in Major Bernier's paper, namely, 
the development of alternate-frame stereo 
techniques, it is, perhaps, worth drawing 
attention to the fact that the majority of 
the basic problems involved were investi- 
gated in England by the writer, Edwin 
Wright and others several years ago. 
Work on such processes has been aban- 
doned by most workers in this country, 
mainly owing to recognition of the fact 
that the disadvantages resulting from 
"time parallax" are inherent in all alter- 
nate-frame systems. 

There are several known methods of 
overcoming the flicker problem, that 
developed by Wright being as satisfactory 
as any; the writer considers it preferable 
to the use of the more complex Morgana 
shuttle movement. A description of 
Wright's method is given in the writer's 
book, Stereoptics An Introduction, Mac- 
donald & Co. Ltd., London, 1951. 

Major Bernier's comments concerning 
the flicker problem are made somewhat 
difficult to follow by this use of phrases 
such as "a flicker frequency of 72 frames/ 
sec, or 36 frames /sec per eye," which do 
not really convey what the author in- 
tended, as the important matter is the 
number of occultations per second rather 
than the number of frames. 

To understand the nature of the flicker 
problem it is essential to appreciate that 
with any projection system, whether stereo- 
scopic or planoscopic, the rate of flicker 
per second is equal to the number of 
times per second that light is occulted from 



each eye. Thus, in ordinary planoscopic 
projection, the flicker rate is equal to the 
product of the number of frames projected 
per second and the number of blades in 
the shutter. When projecting plano- 
scopically at 16 frames per second, for 
example, the flicker rate is 32 or 48 per 
second according to whether a 2-blade or 
3-blade shutter is employed. In neither 
of these two cases is flicker perceptible 
to the eye, so the term "flicker" is really 
a misnomer in such instances. It is readily 
demonstrable that the minimum rate of 
occultation necessary to prevent the 
occurrence of objectionable flicker is about 
24 frames/sec, this rate being achieved 
at a projection speed of 12 frames /sec 
with a 2-blade shutter or 8 frames/sec 
with a 3-blade shutter. 

Now, with stereoscopic systems of the 
type in question, light is occulted from 
each eye every time a picture intended for 
the other eye is projected. This means 
that in addition to the faster, imperceptible 
occultations produced by the shutter, 
there occur occultations at a slower rate 
numerically equal to one-half the number 
of frames projected per second. Ac- 
cordingly, in order to provide the necessary 
minimum of 24 occultations per second for 
each eye, a projection rate of 48 frames per 
second must be adopted, regardless of the 
number of blades in the shutter. As this 
is generally impractical, it becomes neces- 
sary to adopt some arrangement such as 
those used by Wright and Major Bernier. 
The writer ventures, nevertheless, to ex- 
press the opinion that such arrangements 
are not really worth while owing to the 
facts that "time parallax" errors are still 
present and that the apparatus is somewhat 
complex. He would like, in conclusion, 
to draw attention to the new single-film 
polarized light process some particulars 
of which are given in his paper "Stere- 
oscopy in the Telekinema and in the 
Future," which appeared in British Kine- 
matography, 18, No. 6: 172-181, June 1951. 
This would appear to be the most satis- 
factory polarized light process so far 
developed. 

August 30, 1951 L. Dudley 

Odeon Theatre 
Kensington High St. 
London, W. 8, 
England 



71 



Reply to the Letter Above 

The recent letter by Mr. L. Dudley, 
director of the Laboratory, Odeon Theatre, 
London, indicates his confusion in reading 
my paper "Three-Dimensional Motion 
Picture Applications," published in the 
June 1951 issue of this Journal. I would 
therefore like the opportunity to set forth 
in more detail the explanation of certain 
phraseology and certain technical aspects 
with which Mr. Dudley was confused. 

He points out that "there are three 
main groups of processes, which might 
conceivably, but should not be referred 
to as the "composite or lenticulated sys- 
tem," as I did on page 599 in the Journal. 
Although he listed the three main groups, 
he didn't give any indication of how that 
type of three-dimensional photography 
could intelligently be referred to. As I 
see it, each of the groups has one thing in 
common: namely, that a viewing device 
on or near the eyes is not needed to vision 
the three-dimensional results. Each de- 
pends on a medium near the picture sur- 
face to selectively direct the proper views 
of the subject to their respective eyes. 
To produce a stereoscopic vision in the 
brain, this medium is dependent, in all 
cases, on one basic fact, that the eyes 
are displaced. Since the groups, as Mr. 
Dudley refers to them, are therefore 
more or less related, there should, in my 
opinion, be some definite means of re- 
ferring to them. 

I could not find anything in the litera- 
ture which seemed to suitably express 
this phase of stereoscopy, and as a result 
chose to refer to the latest refinements of 
it as the "composite or lenticulated" sys- 
tem. As to the source of the expression 
"composite," it appears in the reference 
book Medical Physics, edited by Otto 
Glasser, Ph.D., Year Book Publishers, 
Inc., Chicago, 1944-1950, on page 1326 
in a treatise on three-dimensional photog- 
raphy. The article under a paragraph 
heading "Tri vision" reads "Early in 1941, 
the Winnek Laboratory introduced a new 
process of composite stereography, now 
called "Trivision." Composite photog- 
raphy, as defined in Webster's New Inter- 
national Dictionary, means a photograph 
or portrait made by a combination, or 
blending of several distinct photographs, 
either made one over the other, or made 



on one print from a number of negatives." 
This, in my opinion, comes very close to 
describing the condition that exists in the 
present picture emulsion of the French 
"Portrait en Relief," the British "Deep 
Pictures," or the American "Trivision," 
and other trade processes, all of which 
stem from the pioneering efforts of H. E. 
Ives (1902), Lippman (1908) and, of 
course, Berthier (1896). 

These refinements of which I speak, 
consist in segregating and resolving (within 
limits), by means of a lenticulated surface 
in front of the emulsion, a continuous 
changing view, or an infinite number of 
views of the subject. Thus, when the 
composite picture is viewed through the 
same or an identical lenticulated surface, 
left and right views are selectively pro- 
jected to their respective eyes. Reasonable 
freedom of movement of the viewing posi- 
tion either laterally or perpendicularly 
to the picture is possible, because any 
two views of the composite, within the 
angle of coverage of the lenticulation 
formula employed, will always be a left 
and right view of the subject, and will be 
directed to the left and right eyes, re- 
spectively. 

The reason, thus, that I referred to this 
phase of three-dimensional photography 
as the "composite" or "lenticulated" 
system is because, in my opinion, this 
phraseology most adequately describes 
this process of three-dimensional photog- 
raphy which in turn has enjoyed limited 
recent popularity as a result of a more 
efficient combined use of these two basic 
features. 

I chose to use "Focus reaction" rather 
than "accommodation" in listing my 
interpretation of the basic factors of depth 
perception, because it seemed to me that 
this expression would be more easily 
understood by the layman, rather than the 
more technical expression "accommoda- 
tion," used almost exclusively in ophthal- 
mic practices. Also, I intended to imply 
that it is not, in my opinion, the difference 
in the character of the focus of objects 
which notifies the brain of their relative 
positions in space, but on the other hand 
the reaction due to the tensing of the 
ciliary muscles. 

In connection with my use of "Stereo- 
scopic vision" as the sixth factor, instead 



72 



of the commonly used phrase "Binocular 
vision," I reasoned that it is possible to 
use "two eyes" in certain cases, but not 
to be able to see stereoscopically. For 
example, the conventional binocular micro- 
scope has two oculars, but only one ob- 
jective; and thus when using such a 
microscope binocularly, one does not see 
stereoscopically. This is also true of some 
binocular viewers for single Kodachrome 
transparencies; also when viewing any 
single photograph or painting binocularly 
the subject matter cannot be seen stereo- 
scopically. Thus it would seem that the 
only requirement to actually view subject 
matter stereoscopically is to change the 
angle of convergence of the eyes for 
different planes of depth. 

We view present two-dimensional color 
motion pictures on the screen with both 
eyes, or binocularly, but we cannot see the 
subject matter stereoscopically because of 
the absence of the requirement to change 
convergence for different planes of depth. 
This would be a case where all the factors 
that Mr. Dudley would like listed could 
be activated, but we still could not see the 
subject matter stereoscopically. This is 
the reason I chose to use "Stereoscopic 
vision" rather than "Binocular vision" as 
the sixth factor of depth perception. 

It seems to me that his reasoning "that 
stereoscopic vision is the net result of the 
various contributing factors" is based on 
a fallacy. Stereoscopic vision is achieved 
in the "Anti-Aircraft stereoscopic height 
finder" without any of the contributing 
factors Mr. Dudley mentions, except the 
"faculty of convergence." The determi- 
nation of the slant range of aircraft in this 
case, depends solely on this factor, and as 
I chose to say "Stereoscopic vision." 

In connection with Mr. Dudley's objec- 
tion to my use of the expression "Optical 
infinity," and that I indicated that it 
could be considered as 20 ft, I would 
like to point out that this is a common 
expression in the field of ophthalmology 
and optometry, and to all American 
trained optometrists the expression imme- 
diately suggests 20 ft, since this theory for 
many years has been and is being taught 
in American colleges and universities (see 
textbook Outline of Optometry by I. M. 
Borish, page 36, Sec. 8 Al, or Physiological 
Optics by W. D. 7oethout, 4th ed., Pro- 



fessional Press, Inc., Chicago, 1947, page 
38, paragraph titled "Principal Foci.") 

The next paragraph of my paper, 
contrary to Mr. Dudley's opinion, is based 
on the fact that there is a direct relation- 
ship between accommodation and con- 
vergence. Namely, that when converged 
at a certain distance, the eyes in a normal 
individual will also automatically focus 
for that distance and vice versa. This 
relationship is thoroughly discussed on 
pages 431 and 432 of A. C. Hardy and 
F. H. Perrin's The Principles of Optics, 
first edition, ninth impression, Camera 
Craft Publishing, San Francisco, 1943. 
Thus, if what Mr. Dudley says is true it 
would seem to me that referring to the 
examples he gives of a film depicting 
objects moving toward or away from the 
observer, that the eyes would also want 
to change convergence. If they change 
their convergence to follow the apparent 
position of this moving object, the result 
would be double imaging. This also 
should occur "with great rapidity," but 
I don't believe it does. I maintain, as 
indicated in my paper, that as long as 
subject matter in the three-dimensional 
motion picture appears no closer than 6 or 
8 ft from the observer, accommodation 
errors will not result. I cannot agree 
with Mr. Dudley on the cause of headaches 
amongst some older people who go to 
the movies, since it is common knowledge 
in ophthalmic practice that they lose 
their power of accommodation as a result 
of progressive hardening of the crystalline 
lens as they grow older. This would 
indicate to me that as long as they were 
wearing glasses corrected for the screen 
distance, the subject matter on the screen 
would remain always in focus. Therefore 
it is interesting to note that when this be 
the case, especially with three-dimensional 
motion pictures, they will see subject 
matter clearly even when required to 
converge on three-dimensional screen ob- 
jects, which could conceivably appear 
as close as two or three feet in front of 
their faces. As an added prediction, 
they will quickly realize that for such a 
phenomenon, they will not need to "peer" 
through their "bifocals." 

I prefer not to disclose as yet what im- 
provements have been made in connection 
with the alternate frame system. However, 
I would like to assure Mr. Dudley that the 



73 



"time parallax" problem has been com- 
pletely solved, and that the alternate 
frame principle with the latest modifica- 
tions shows promise, in my opinion, of 
being the most all-around satisfactory 
stereoscopic motion picture method to 
date. 

In regard to my use of the phrase "a 
flicker frequency of 72 frames/sec, or 36 
frames/sec per eye," I would like to clear 
up Mr. Dudley's apparent confusion in 
respect to the action of the Morgana 
movement. This movement, I made 
quite clear in my paper, actually transports 
frames of film in and out of the film gate 
at the rate of 72 frames/sec. This rate 
of frame transport is, therefore, exactly 
coincident with the shutter-blade rate, 
and therefore is also identical to the total 
"occultation" rate. Thus the right frames, 
for example, are transported in and out 
of the film at the rate of 36 frames /sec, 
which also equals the "occultation" rate 
for that eye, per second. Since, then, the 
actual framing rate is also equal to the 
flicker rate, I believe it reasonable to 
express the flicker frequency in terms of 
"frames per second." As I pointed out in 
my paper, since every third transport 
consists in moving a "frame backwards" 
out of the gate, the net result is a "pro- 
gression of the film through the projector 
at standard sound speed." 



Again I cannot agree with Mr. Dudley's 
contention that "the minimum rate of 
occultation necessary to prevent the 
occurrence of objectionable flicker is 
about 24 per second." If this were true 
it would not be necessary to use a two- 
bladed shutter in standard theater-type 
projectors, which in turn doubles the 
occultation rate with respect to the 
"24/sec" frame rate. 

When the film 3 D Motion Pictures was 
screened at the SMPTE 1951 Spring Con- 
vention, some may recall that there still 
remained some flicker. This was due to 
the comparatively slow flicker frequency of 
36 frames/sec per eye. This frequency 
was somewhat objectionable, and to bring 
it up to present standards, improvements 
had to be made. A new projector, which 
will incorporate important changes will 
be ready to demonstrate in the near future. 



November 14, 1951 



Robert V. Bernier, Major, 
U.S.A.F., 

Hq. Wright Air Develop- 
ment Center, 
Box 7145, Area B, 
Wright-Patterson AFB, 
Dayton, Ohio 



Obituary 



Charles Ross died in June at the age of 
63. He was President and sole owner of 
Charles Ross, Inc., a business which he 
started 30 years ago. 

He began working for motion picture 
studios in New York City when a boy, 
one of his early employers having been 
the Biograph Studios. He was an elec- 
trician and he gradually built up stocks of 
everything from cables to equipment 
which eventually included every type of 
lighting or grip equipment for motion 
picture production. 

He was educated in the New York public 
schools and some time after he had begun 
his business he and Pete Mole discovered 
in mutual reminiscing that they had 



grown up in the same New York City 
neighborhood and gone to the same 
schools without then being acquainted. 
Charles Ross, Inc., has now for long been 
sole eastern agents for Mole-Richardson 
equipment. The firm's headquarters at 
333 W. 52 St., New York 19, N.Y., is in 
the same neighborhood where Mr. Ross 
had offices and warehouse during his 
decades in business. 

Besides being an Active Member of this 
Society, Charles Ross was a member of 
Motion Picture Pioneers, Theatre Equip- 
ment and Supply Manufacturers' Associa- 
tion, Stage Employees' Local #1 of the 
IATSE and Motion Picture Studio Me- 
chanics Local #52 of the IATSE. 



74 



New Members 



The following members have been added to the Society's rolls since those last published. 
The designations of grades are the same as those used in the 1952 MEMBERSHIP DIRECTORY. 
Honorary (H) Fellow (F) Active (M) Associate (A) Student (S) 



Allen, James M., Cinematographer, 
Sandia Corp. Mail: 223 La Merced 
Ave., Albuquerque, N.M. (A) 

Almond, W. Ritchie, Building and Main- 
tenance of Technical Equipment, 
Hungerford Laboratories, Inc. Mail: 
358 Norwich Dr., West Hollywood, 
Los Angeles 48, Calif. (A) 

Althouse, Clinton R., Television-Radio 
Technician and Engineer. Mail: 1540 
N. Sierra Bonita Ave., Hollywood 46, 
Calif. (A) t 

Bailey, Marvin L., Film Editor, Sarra. 
Mail: 5730 N. Ridge Ave., Chicago 40, 
111. (M) 

Barry, John W., Television Film Director, 
Station WLTV. Mail: 227 Second 
Ave., Decatur, Ga. (M) 

Beaulieu, J. W. Roland, Supervisor, FM- 
Transmitters, Canadian Broadcasting 
Corp. Mail: 4505 Cote des .Neiges 
Rd., Apt. 8, Montreal, Que., Canada. 
(M) 

Belok, Alfred, Color Consultant and 
Technician, 112-20 Beach Channel Dr., 
Rockaway Park, L.I., N.Y. (A) 

Bemis, Russell W., Designer, Dept. of 
Architecture and Engineering, Uni- 
versity of California at Los Angeles. 
Mail: 8424 Lennox Ave., Van Nuys, 
Calif. (A) 

Bennett, Ralph S., Audio- Video Facilities 
Engineer, National Broadcasting Co. 
Mail: 51 Ellenton Ave., New Rochelle, 
N.Y. (A) 

Bennett, Lt. Wallace C., Motion Picture 
Section, U.S. Air Force. Mail: 21539 
W. Lake Rd., Rocky River, Ohio. (A) 

Benton, Charles E., Jr., Photographic 
Technologist, Assistant Chief, Photo- 
graphic Technical Section, Naval Re- 
search Laboratory. Mail: 4200 52 
St., Decatur Heights, Bladensburg, Md. 

Berryhill, Joseph L., Television Engineer, 
Technical Supervisor, KRON-TV. 
Mail: 143 Ridge Rd., San Anselmo, 
Calif. (M) 

Bevins, Ralph S., Assistant Sound Tech- 
nician, Byron, Inc. Mail: 2709 S. 
Wayne St., Arlington, Va. (A) 

Bristol, Christopher, University of South- 
ern California. Mail: 1184 W. 39 
St., Los Angeles 37, Calif. (S) 

Carlson, George M., Motion Picture Film 
Developer, Byron, Inc. Mail: 137-35 
St., N.E., Washington, D.C. (A) 



Cobun, Charles C., Certified Public 
Accountant, Senior Partner, Graves & 
Cobun. Mail: 2504 W. 79 St., Ingle- 
wood 4, Calif. (A) 

Cohlan, Bernard F., Consulting Engineer, 
719 Gayey Ave., Los Angeles 24. (M) 

Crowell, F. E., Flight Test Photographer, 
Boeing Airplane Co. Mail: 8426 
22d S.W., Seattle 6, Wash. (A) 

Daines, Eric Norman, Sound Recording 
Engineer, British Lion Studio Co., Ltd. 
Mail: 2 St. Mary's Rd., Ealing, W. 5, 
London, England. (A) 

Dauglash, William J., Sub-Manager and 
Engineer, Westrex Co., Ltd. Mail: 
675 Florentino Torres, Manila, Philip- 
pines. (A) 

De Poix, G., President, Bauchet et Cie. 
Mail: Vert Bois, Rueil-Malmaison, 
Seine et Oise, France. (A) 

Eggers, Walter G., In Charge, Sensito- 
metric Control, Mecca Film Labora- 
tories, Inc. Mail: 235 E. 85 St., New 
York 28, N.Y. (A) 

Engel, Walter J., Executive, Motion Pic- 
ture Cameraman, Walter Engel Studios, 
Inc., 20 W. 47 St., New York 19. (M) 

Esh, Raymond M., Wilding Picture Pro- 
ductions Inc. Mail: 1664 Spruce Ave., 
Des Plaines, 111. (A) 

Evans, A. E., Engineering Manager, 
American Broadcasting Co. Mail: 2823 
Kelly Ave., Hayward, Calif. (M) 

Foley, Robert R., Electronics Engineer. 
Bell & Howell Co. Mail: 508 S! 
Humphrey Ave., Oak Park, 111. (A) 

Gavin, Roy J., Sales Manager, Minnesota 
Mining & Manufacturing Co., 3M Co.. 
900 Fauquier St., St. Paul 6, Minn. 
(M) 

Gell, Hugh Digby, Service Engineer and 
Projectionist, Thomas O'Brien. Mail: 
2 Henry St., KEW. E. 4, Melbourne, 
Australia. (A) 

Greig, Arthur W., Engineer, Mar. Broad- 
casting Co. Mail: 13 Newton Ave., 
Halifax, Nova Scotia. (A) 

Havill, Percy C., Projectionist, Beck 
Theatre Corp. Mail: 918 Sunnyside 
Ave., Chicago, 111. (A) 

Hess, Stanley R., TV Manager, Wasser, 
Kay & Phillips. Mail: 265 Ashland 
Ave., Pittsburgh 28, Pa. (M) 

Hilliard, Joseph Q., Chief, Optics Section, 
Instrumentation Unit, Air Force Missile 
Test Center. Mail: 266 Oleander 
La., Eau Gallic, Fla. (M) 



75 



Holmes, Frank A., Color Film Duplicat- 
ing, 7619 Sunset Blvd., Los Angeles 
46, Calif. (A) 

Horsley, David S., Director of Special 
Photography, Universal-International 
Pictures Co. Mail: 3846 Willowcrest, 
North Hollywood, Calif. (M) 

Hughes, Dale E., Film Producer, 186 E. 
Center St., Marion, Ohio. (A) 

Jaeger, Donald J., University of Southern 
California. Mail: 2300 Cahuenga 
Blvd., Los Angeles, Calif. (S) 

James, Stanley L., Projectionist and Sound 
Technician, United Amusement Co. 
Mail: 6 Carolina St., S., Hamilton, 

' Ont., Canada. (A) 

Jay son, Richard N., Color Motion Picture 
Laboratory, Colorfilm, Inc. Mail: 20 
Dogwood Ter., Livingston, NJ. (M) 

Johnston, Andrew G., Motion Picture 
Cameraman, Byron, Inc. Mail: 7325 
Forest Rd., Hyattsville, Md. (A) 

Kaplan, Neil K., University of Southern 
California. Mail: 7760 Hollywood 
Blvd., Apt. 311, Hollywood 46, Calif. 
(S) 

Keehn, Neal G., 16mm Film Production, 
The Calvin Co. Mail: 112 W. 61 
Ter., Kansas City 2, Mo. (A) 

Kellum, Theron O., Re-recording Mixer, 
RKO Radio Pictures, 780 N. Gower 
St., Hollywood 38, Calif. (M) 

Kezer, Charles F., Engineer, Fairchild 
Recording Equipment Corp., 154 St. 
& Seventh Ave., Whitestone, N.Y. 
(A) 

Kudar, John C., 1809f Las Palmas Ave., 
Hollywood 28, Calif. (A) 

Langley, Frank P., Jr., Optical-Electrical 
Engineer, Research Div., Philco Corp. 
Mail: 708 Brooke Rd., North Hills, 
Pa. (A) 

Lewis, Herschell G., Radio-TV Pro- 
ductions, Lewis & Clark, Inc., 1020 N. 
Rush St., Chicago 11, 111. (A) 

Liebers, Harold A., 307 Martense St., 
Brooklyn 26, N.Y. (A) 

Lindsay, Leslie C., Audio and Television 
Technician, Leslie C. Lindsay & Asso- 
ciates. Mail: Steeles Corners, R.R. 
#1, York Mills, Ont., Canada. (A) 

Manohar, M. D., 41 Lokamanya Co- 
operative Society, Bombay 16, India. 
(M) 

Mellott, Albert, University of Southern 
California. Mail: 942 W. 34 St., 
Los Angeles 7, Calif. (S) 

Meredith, John F., Producer, Ambassador 
Films. Mail: 6648 Odell Ave., Chicago 
31, 111. (A) 

Moscaret, Joseph A., New York Uni- 
versity. Mail: P.O. Box #54, Kew 
Gardens 15, N.Y. (S) 



Murray, Capt. John T., Motion Picture 
Laboratory Supervisor, U.S. Air Force. 
Mail: 5606 36 PL, Hyattsville, Md. 
(A) 

Nadeau, Arsene G., Chief Engineer, 
Radio Station CHRC, Ltd. Mail: 11 
St. Benoit St., Quebec, P. Que., Canada. 
(A) 

O'Brien, Robert H., Motion Pictures and 
Television, United Paramount Theatres, 
Inc., 1501 Broadway, New York 18. 
N.Y. (M) 

O'Toole, Russel, Sound Engineer, RCA 
Service Co. Mail: 1321 Spear, Logans- 
port, Ind. (A) 

Paney, Harry E., Director, Photographic 
Dept., Moody Bible Institute, 820 N. 
La Salle St., Chicago 10, 111. (A) 

Potter, Stannard M., Assistant Project 
Engineer, Pratt & Whitney Aircraft, 
Experimental Test 2, East Hartford, 
Conn. (M) 

Quinn, J. T., Chief Engineer, Wired 
Broadcasting & Television, Rediffusion, 
Inc., 1085 Beaver Hall Hill, Montreal, 
Que., Canada. (M) 

Rector, Eugene, Projectionist, Fox Mid- 
west Theatres. Mail: 309 Crawford, 
Ft. Scott, Kan. (M) 

Robinson, Thomas J., Motion Picture 
Photographer, Naval Research Labora- 
tory. Mail: 3529 S. Utah St., Apt. 
B-l, Arlington, Va. (A) 

Rogers, Ralph L., Motion Picture Camera- 
man, Baptist Sunday School Board. 
Mail: 161 Eighth Ave., N., Nashville 
3, Tenn. (A) 

Roggenburg, Stanley L., Jr., Chemist, 
E. I. du Pont de Nemours & Co., Inc. 
Mail: 621 Ocean Ter., Staten Island 1, 
N.Y. (A) 

Salter, Victor M., Physicist, E. I. du Pont 
de Nemours & Co., Inc. Mail: 31 
Spring Ter., Red Bank, NJ. (M) 

Schneider, Joseph, University of Southern 
California. Mail: 1255 N. Sycamore 
Ave., Hollywood 38, Calif. (S) 

Sheldon, E. E., Physician, 490 West 
End Ave., New York, N.Y. (A) 

Sherman, Alan E., Illinois Institute of 
Technology. Mail: 3254 S. Michigan 
Ave., Chicago 16, 111. (S) 

Shino, J. S., Electronics Laboratory Tech- 
nician, Miltstark, Ltd. Mail: 48 W. 
Lynn Ave., Toronto 6, Ont., Canada. 
(A) 

Siegel, Reuben S., Chemist, Signal Corps 
Photographic Center. Mail: 737 E. 
48 St., Brooklyn 3, N.Y. (A) 

Slay maker, Frank H., Chief Sound Equip- 
ment Engineer, Stromberg-Carlson Co 
Mail: 1225 Clifford Ave., Rochester, 
N.Y. (M) 



76 



Smith, Wallace T., Field Test Super- 
visor, Sandia Corp. Mail: Ventana 
Grande, Sandoval, N.M. (M) 

Sorey, Lt. J. H., Head, Motion Picture 
Processing Div., U.S. Naval Photo- 
graphic Center, Naval Air Station, 
Anacostia 20, D.C. (M) 

Spruill, Dudley, Motion Picture Tech- 
nician, Byron, Inc. Mail: 9601 Page 
Ave., Bethesda, Md. (A) 

Stalling*, Peyton M., Director, The Calvin 
Co., 1105 E. 15 St., Kansas City, Mo. 
(M) 

Strickland, C. Louie, General Manager, 
Strickland Film Co. Mail: 2592 Christ- 
mas La., N.E., Atlanta 6, Ga. (A) 

Takahash, Tom H., Photographer, Sandia 
Corp. Mail: 631 W. McKnight, Albu- 
querque, N.M. (A) 

Tyner, H. P., Sound Engineer, RCA 
Service Co. Mail: 1907 McKinney 
Ave., Dallas, Tex. (A) 

Valentino, Thomas J., General Manager, 
Thomas J. Valentino, Inc., 150 W. 
46 St., New York 36, N.Y. (M) 

Varnum, [ennison, Sound Technician, 
Radio Station KLAC. Mail: 1618 
Tulare Ave., Burbank, Calif. (A) 

Ver Halen, C. J., Jr., Publisher, Ver 
Halen Publishing Co., 1159 N. Highland 
Ave., Beverly Hills, Calif. (M) 



Wagner, Richard J., Sound Technician, 
Paramount Pictures Corp. Mail: 5661 
Lemon Grove, Hollywood 38, Calif. 
(A) 

Wallace, Sj?t. Melvin, U.S. Army. Mail: 
870 E. 170 St., New York 59, N.Y. (A) 

Weiner, James R., Chief Engineer, Rem- 
ington Rand, Inc., Eckert-Mauchly 
Div., 2300 W. Allegheny Ave., Phila- 
delphia, Pa. (A) 

Wetzel, W. W., Technical Director, 
Minnesota Mining & Manufacturing 
Co. Mail: 725 Ridge St., St. Paul, 
Minn. (M) 

Wieder, Harold, Optical Engineer, Radio 
Corporation of America, RCA Labora- 
tories Div., Princeton, N.J. (A) 

Wooten, Eugene W., Studio Relations, 
Cinecolor Corp. Mail: 1331 Monaco 
Dr., Pacific Palisades, Calif. (M) 

Yuskaitis, Robert J., Owner, Eagle 
Laboratory, 1732 N. Orchard St., 
Chicago 54, 111. (A) 

CHANGES IN GRADE 

Atkinson, R. B., (A) to (M) 
Beard, D. M., (A) to (M) 
Bernard, H., (S) to (A) 
Blaney, Dorothy, (A) to (M) 
Flory, John, (A) to (M) 
Pfahler, R. A., (A) to (M) 
Riley, L. W., (A) to (M) 



Book Reviews 



Proceedings of the National 
Electronics Conference, Vol. 7 

Published (1951) by National Electronics 
Conference, Inc., 852 E. 83 St., Chicago 
19, 111. 736 pp. incl. numerous charts, 
diagrams and tables. 6 X 9 in. Price 

$5.00. 

This volume consists of the papers 
presented at the seventh annual National 
Electronics Conference held in Chicago 
in the fall of 1951. The topics presented 
cover just about the entire field of modern 
electronics as can be seen by the subsequent 
listing of subjects, and are extremely timely 
to anyone working in the field. Your 
reviewer found at least a dozen papers 
that had direct bearing on immediate 
problems. 

The subjects covered include servo 
theory, electron tubes, information theory, 
audio systems, signal detection, com- 
ponents, high-frequency measurements and 



propagation, computers, magnetic ampli- 
fiers, circuit analysis, industrial electronics, 
television, and medical applications. 

The editors of the volume are to be 
commended for a fine job in taking the 
numerous papers from different authors 
on various topics and organizing them so 
as to maintain continuity, especially in 
style. This represents a continuation of 
the good work done in the previous volumes 
of this series. 

The book is printed clearly and the 
illustrations are very legible. 

This well prepared and edited volume of 
the Conference papers will serve either as 
a well reported summary to those who were 
unable to attend the meeting, or as a 
convenient reference volume for those 
who were there. It would be very de- 
sirable if other major conferences would 
publish similar proceedings. H. L agor, 
General Precision Laboratory, Inc., Pleas- 
antville, N.Y. 



77 



Professional Training 
of Film Technicians 

By Jean Lods. Published (1951) by 
UNESCO, Paris. Distributed in U.S.A. 
by: Columbia Univ. Press, 2960 Broad- 
way, New York 27, N.Y. 155 pp. 8f X 
5i in. Price $1.00. 

A valuable addition to the Press, Film 
and Radio Series of studies sponsored by 
the United Nations Educational, Scientific 
and Cultural Organization, this brochure 
surveys a field whose importance has 
only recently been recognized in this 
country. 

Its author is a distinguished French 
film director, cofounder and Deputy 
Director-General of the Institut des Hautes 
Etudes Cinematographiques, a Government- 
subsidized postgraduate school devoted 
to the teaching of film aesthetics and 
crafts. 

In the ten countries investigated, states 
Mr. Lods, "professional training is directly 
conditioned ... by the situation, organiza- 
tion and tendencies of the national film 
industry." The latter, he finds, is divided 
into three main types, depending on the 
degree of government control. 

This control may vary considerably, 
but the author points out the universally 
admitted fact that "the quality of national 
film production is a matter of concern to 
the entire country." Therefore, national 
prestige is closely related to the competence 
of film technicians and their professional 
training. 

In this respect, the high standards of 
the French Institut can be judged by the 
following question asked at the competitive 
entrance examination for art directors: 
"Voltaire's 'smile' is often mentioned. 
Define and analyze this smile on the basis 
of Candide. Relate it to a frame of mind 
generally characteristic of the 18th cen- 
tury." George L. George, Screen Directors 
Guild, 133 E. 40 St., New York 16, N.Y. 



Fluorescent Lighting 

By W. Elenbaas, J. Funke, Th. Hehen- 
kamp, L. C. Kalff, A. A. Kruithof, J. L. 
Ouweltjes, L. M. C. Touw, D. Ver- 
meulen and R. Van Der Veen. Edited 
by C. Zwikker. Published (1952) by 
N. V. Philips' Gloeilampenfabrieken, Eind- 



hoven, Netherlands. Distributed in U.S.A. 
by Elsevier Press, Inc., 402 Lovett Blvd., 
Houston 6, Tex. i-x + 244 pp. + 4 pp. 
index. 180 illus. + 23 photos. 6X9 
in. Price $6.25. 

The book reviews the scientific funda- 
mentals of the design and operations of 
fluorescent lamps and accessory equip- 
ment, in terms of types and sizes used in 
Europe. Chapters on fixtures and fluo- 
rescent lighting applications are likewise a 
report of European practice. 

The section on color and color renditions 
is a good summary of the fundamental 
technology involved. The spectral data 
on fluorescent sources, however, are based 
on lamps manufactured in the Nether- 
lands. Motion picture and television 
engineers will find the book a convenient 
way to compare European practice with 
U.S. practice as reported in books and 
periodicals published in this country. 
C. L. Amick, Lamp Div., General Electric 
Co., Nela Park, Cleveland 12, Ohio. 



The Recording and Reproduction 
of Sound (2d ed.) 

By Oliver Read. Published (1952) by 
Howard W. Sams & Co., Indianapolis 1, 
Ind. i-xv + 708 pp. + 70 pp. appendix + 
10 pp. index. 708 illus. 6 X 9 in. Price 

$7.95. 

This volume contains a large amount of 
information which should be of interest to 
audio hobbyists and engineers in audio and 
related fields. The sections on disc 
recording and reproducing systems are 
quite complete and magnetic recording 
is also covered in considerable detail, 
although no mention is made of recording 
on "stripe" tracks on 8mm or 16mm films. 
Photographic recording is barely men- 
tioned. Public address amplifiers and 
sound systems are treated at some length, 
as are microphones and loudspeakers. 

Much space is given to reprints of 
manufacturer's bulletins, which may be 
of interest to those using the particular 
equipment described. The NARTB Disc 
and Magnetic Recording Standards are 
reproduced in full and numerous tables 
and glossaries add to the usefulness of this 
enlarged edition. Clyde R. Keith, 5 North 
Ter., Maple wood, N.J. 



78 



SMPTE Lapel Pins 



The Society will have available for mailing after September 15, 1952, its gold and blue 
enamel lapel pin, with a screw back. The pin is a ^-in. reproduction of the Society 
bol the film, sprocket and television tube which appears on the Journal cover. 
The price of the pin is $4.00, including Federal Tax; in New York City, add 3% 
tax. 




Positions Wanted 



Photographic Chemist: 3 yr. experience black-and-white and color film laboratory 
practice and quality control. Familiar with all commercial color processes and sensi- 
tometry. Have conducted research in new processing methods. Position desired in 
research or development on new products and processes. Will relocate. Write M-52, 
c/o Lichtig, 3758 Tenth Ave., New York 34, N.Y. 

Production, TV or Motion Picture: NYU BA in motion picture and TV production; 
participated in productions as director and unit mgr; experience as motion picture 
sensitometrist ; at present motion picture negative assembler and cutter; worked swing 
shift while attending college; licensed 35mm projectionist; single, 29, veteran, resume 
on request; go anywhere. Harold Bernard, 560 Eastern Pkwy, Brooklyn 25, N.Y. 



Meetings 



72nd Semiannual Convention of the SMPTE, Oct. 6-10, Hotel Statler, 

Washington, D. C. 

Other Societies 

University Film Producers Association, Annual Meeting, Aug. 11-15, Syracuse Univer- 
sity, Syracuse, N. Y. 

Photographic Society of America, Annual Convention, Aug. 12-16, Hotel New Yorker, 

New York 

American Institute of Electrical Engineers, Pacific General Meeting, Aug. 19-22, Hotel 

Westward Ho, Phoenix, Ariz. 

International Society of Photogrammetry, Conference, Sept. 4-13, Hotel Shoreham, 

Washington, D.C. 

American Standards Association, Third National Standardization Conference, Sept. 

8-10, Museum of Science and Industry, Chicago, 111. 

Illuminating Engineering Society, National Technical Conference, Sept. 8-12, Edge- 
water Beach Hotel, Chicago, 111. 

Biological Photographic Association, Annual Meeting, Sept. 10-12, Hotel New Yorker, 

New York 

National Electronics Conference, Annual Meeting, Sept. 29-Oct. 1, Sherman Hotel, 

Chicago, 111. 

Optical Society of America, Oct. 9-11, Hotel Statler, Boston, Mass. 

American Institute of Electrical Engineers, Fall General Meeting, Oct. 13-17, New 

Orleans, La. 
American Standards Association, Annual Meeting, Nov. 19, Waldorf-Astoria, New York 

Motion pictures in color depend on the engineers' knowledge of the "Principles of 
Color Sensitometry." A 72-page article bearing that title and prepared by the Color 
Sensitometry Committee appeared in the Journal for June 1950. Attractive reprint 
copies may be purchased for SI. 00. 

79 



New Products 



Further information about these items can be obtained direct from the addresses given. 
As in the case of technical papers, the Society is not responsible for manufacturers' state- 
ments, and publication of these items does not constitute endorsement of the products. 




Eidophor large-screen, color-television projection equipment: (1) Eidophor pro- 
jector; (2) projection light beam hood; (3) color wheel; (4) auxiliary services (vacuum 
pump, thermostat, and system for Eidophor cooling); (5) projection lamp (Ventarc- 
type) ; and (6) television receiver circuits. 



Eidophor large-screen, color-television 
projection equipment has been installed 
in the 20th Century-Fox Film Corp. 
motion picture theater at 444 W. 56th 
St., New York City, with demonstrations 
for the press and invited public beginning 
on June 25. A 30-min program of great 
variety and color was originated and 
transmitted from the sound stages of 
Movietonews at W. 54 St. and Tenth Ave. 

- Journal readers may recall the article 
by E. Labin in the April 1950 Journal 
when the Eidophor was described as 
occupying two floors. Work toward the 
Eidophor was described as early as 1941 
by Hugo Thiemann and by Prof. Fritz 
Fischer who directed the project until 
his death in 1948. The Eidophor was 
developed at the Polytechnical Institute 
of Zurich, Switzerland, and was brought 
to this country in part through the efforts 
of Dr. Edgar Gretener A.G. of Zurich, 
and by Dr. Thiemann who was on hand to 



answer questions during the demonstra- 
tions at Twentieth Century-Fox. 

The present Eidophor projector is about 
the size, weight and shape of a standard 
motion picture projector. The Eidophor 
has a Ventarc-type projection lamp 
which was demonstrated at the Society's 
Convention at Chicago in 1950 and 
described in the October 1950 Journal. 
The Columbia Broadcasting System's field- 
sequential color process has been combined 
with the Eidophor black-and-white equip- 
ment. The CBS system was completely 
described in, among other places, the 
October 1951 Journal by Goldmark, 
Christensen and Reeves. 

Converting the original black-and-white 
Swiss system to the color demonstrated 
and getting the present model developed 
and installed has been under the direction 
of Earl I. Sponable, with notable assistance 
from Hubert J. Schlafly, Lorin D. Grignon 
and William F. Jordan. 



80 



Op timum Exposure of Sound Tracks 
on Kodachrome Films 

By ROBERT C. LOVIGK 



Low-distortion sound tracks on Kodachrome films can be obtained with any 
conventional exposure method. The best possible sound reproduction re- 
quires exposure with light of color quality which correlates the speeds of the 
individual emulsions when developed to silver sulfide rather than to dyes. 
Poor sound quality in the past has often been the result of the.failure to recog- 
nize the critical color quality requirement of the light which exposes the 
sound-track portion of the film. 



.ODACHROME Duplicating Color Film, 
Type 5265 is a 16mm, reversal film de- 
signed to be printed from color positives 
on Kodachrome Films, Daylight Type 
(5263), Type A (5264), and Kodachrome 
Commercial Film (5268). The sound- 
track deposit is silver sulfide. The sound- 
track record is printed from silver posi- 
tives prepared according to long-stand- 
ing recommendations. 

The sound process for Kodachrome 
films consists of three basic steps. First, 
the silver halides which were exposed in 
the sound-track printer are developed to 
a silver negative image. Second, thesilver 
halide which remains is converted to silver 
sulfide. Third, the negative silver is dis- 
solved, leaving a reversal silver sulfide 
image. 

There are many complicating factors 

Presented on April 24, 1952, at the Society's 
Convention at Chicago, 111., by Robert C. 
Lovick, Color Control Div., Eastman 
Kodak Co., Rochester 4, N. Y. 



in this basically simple process. For 
example, the necessity of confining the 
sound developer to the sound-track area 
within small tolerances precludes the 
use of agitation to aid in securing uniform 
development. 

Recent studies have shown that a large 
part of the stain level of Kodachrome 
sound records results from conversion of 
some of the negative silver to silver sul- 
fide. A modified developer which con- 
verts a much smaller part of the negative 
silver to silver sulfide is now being used. 
There is a small improvement of signal- 
to-noise ratio which is the result of the 
increased useful transmission range. The 
sensitometric effect of the sound de- 
veloper modification is shown in Fig. 1. 

Standardized Printing Methods 

Printing to obtain the best possible 
sound tracks on Kodachrome films re- 
quires consideration of three facts. 
First, the exposures are made on a multi- 
layer film. Second, the three emulsion 



August 1952 Journal of the SMPTE Vol. 59 



81 



I ,.0 



oo 



0.5 



.OLD TYPE 

Sulfide Developer 



MODIFIED^ 
Sulfide Developer^ 



LOG E 
Fig. 1. Sensitometric effect of modified silver sulfide developer. 



layers are sensitized to respond princi- 
pally to three different colors of light. 
Third, the speed relationships of the 
layers are determined by the charac- 
teristics desired for the dye formation for 
pictures while sound-track development 
converts the halides in all layers to silver 
sulfide, a much different material. 

Sound tracks on Kodachrome films 
are usually printed using a conventional 
sound printer with adjustments of the 
printer lamp current to obtain a partic- 
ular density. Changing the printer 
lamp current results in the simultaneous 
change of both the intensity and the color 
quality of the light source. Since the 
efficiency of different optical systems 
varies considerably, and since many dif- 
ferent types of lamps and heat absorbers 
are in use, it is almost impossible to give 
any information, such as a filter balance, 
which can be applied without further 
extensive tests on the particular equip- 
ment involved. 

Standardizing the light source for 
sound-track printing requires very little 
additional control work for most labora- 
tories and makes possible the use of print- 



ing recommendations without extensive 
tests. If conventional distortion tests 
can be made, there is still a considerable 
saving of time and film because an ex- 
cellent starting place is available for ad- 
justing the exposure balance for partic- 
ular equipment. Should emulsion 
changes become necessary or desirable, 
the extent of filter-pack modification 
could be specified, reducing appreciably 
the need of additional time- and film- 
consuming tests. 

A fixed color temperature of 2900 K 
for a tungsten source is suggested be- 
cause it is well within the rating of most 
lamps and because experience has indi- 
cated that more than enough light is 
available on almost any printer. Heat- 
absorbing glasses may greatly modify the 
spectral energy distribution of the light 
source. Heat-absorbing glasses should 
be Pittsburgh 2043, 2 mm thick or an 
equivalent filter. Adjustments of in- 
tensity are made by neutral density 
filters or diaphragms or both, depending 
on the particular printer. The final ad- 
justment of color quality is made with 
Kodak Color Compensating Filters, but 



82 



August 1952 Journal of the SMPTE Vol. 59 



30 



20 



10 




0.4 0.5 0.6 0.7 

DENSITY (of 8OOm//) OF UNMODULATED, UNBIASED AREA 



0.8 



Fig. 2. Intel-modulation. Unfiltered light of 2900 K tungsten source. 



these filters are not part of the standard 
source. 

Kodak Color Compensating Filters 
are gelatin niters and should be protected 
from heat as much as possible. Heat- 
absorbing glasses should be between the 
light source and the filters and physically 
separated as much as possible. Addi- 
tional air-cooling of the filters is desirable 
and may be absolutely required in some 
printers. 

The color compensating filters are a 
necessary part of the filter pack for print- 
ing sound on Kodachrome films. The 
capabilities of printed Kodachrome film 
for sound reproduction are much better 
than previous investigators 1 - 2 have re- 
ported, primarily because so little at- 
tention was paid to the color quality of 
?the light used in exposing the sound 
track. The color quality must coordinate 
the speeds of the three layers or the best 
sound quality will not be obtained. 

Determination of Exposure Conditions 
for Optimum Sound Quality 

Distortion of variable-density prints 
was determined by the intermodulation 



method 3 using conditions prescribed by 
American Standard Z22.51. The nega- 
tives employed were sensitometrically 
normal negatives suitable for printing on 
black-and-white release positive film. 
A negative on Eastman Fine Grain Sound 
Recording Film, Type 5373 was exposed 
and processed for a gamma of 0.55 and 
density of 0.55. This negative was 
printed on Eastman Fine Grain Release 
Positive Film, Type 7302 and processed 
to a density of 0.55 and gamma of 2.50. 

Variable-area distortion was deter- 
mined by the cross-modulation test 4 with 
conditions prescribed by American Stand- 
ard Z22.52. This standard designates a 
4000-cycle carrier frequency amplitude- 
modulated at 400 cycles/sec. The nega- 
tives used were prepared on Eastman 
Fine Grain Sound Recording Film, 
Type 5372, with a gamma of 3.65 and 
total diffuse visual density of 2.98. The 
negatives were printed onto Eastman 
Fine Grain Release Positive Film, Type 
7302 to a gamma of 2.48 and density of 
2.0. 

A Western Electric RA-1100B Densi- 
tometer was used for all density measure- 



Robert C. Lovick: Sound Tracks on Kodachrome 



83 




0.4 0.5 0.6 0.7 0.8 

DENSITY (at 600m//) OF UNMODULATED, UNBIASED AREA 

Fig. 3. Intel-modulation. Filtered light of 2900 K tungsten source. 




0.4 0.5 0.6 0.7 0.8 

DENSITY (at 800m//) OF UNMODULATED. UNBIASED AREA 

Fig. 4. Intel-modulation. Filtered light of 2900 K tungsten source 
using stronger filters in the printing beam than shown in Fig. 3. 



84 



August 1952 Journal of the SMPTE Vol. 59 



merits. A visual sensitivity characteris- 
tic was used for all black-and-white 
materials. The instrument was con- 
verted to provide diffuse density measure- 
ments at 800 m/i for densitometry of the 
silver sulfide deposit on the Kodachrome 
films. 5 

Low-distortion sound records on Koda- 
chrome films can be obtained with any 
conventional exposure method. The 
quality of sound reproduction which can 
be obtained is controlled by the color 
quality of the light which exposes the 
film in the sound printer. 

The intermodulation curve shown in 
Fig. 2 was obtained by measurements of 
Kodachrome Duplicating Color Film, 
Type 5265. This curve resulted from 
exposure with the standard light source 
previously mentioned but without addi- 
tional color-compensating filters. The 
only variable in this exposure was the 
intensity of the printing light. A com- 
mon error has been to assume, after 
obtaining such a curve, that this repre- 
sents the best that could be expected from 
printed sound tracks on Kodachrome 
film. 

The series of intermodulation curves 
in Fig. 3 were obtained from measure- 
ments of Kodachrome film which had 
been exposed to different color qualities 
of light. The curve marked 30Y shows 
per cent intermodulation for film ex- 
posed to the standard 2900 K source 
with a GG-30 Yellow filter in the printing 
beam. Intensity changes were made 
with carbon-deposit, neutral-density 
niters. 

The intermodulation curves shown in 
Fig. 4 were obtained from measurements 
of film which had been exposed using 
stronger filters in the printing beam. 
The curve obtained by printing with the 
standard source plus Kodak Color Com- 
pensating Filters equal to CC-70 Yellow 
resulted in an intermodulation level of 
4%. This low level of distortion was 
obtained at a density at 800 rmi of 0.6 
(diffuse visual density of 1.4). This is 



the same density for which the minimum 
in Fig. 2 was 19%. 

One of the most important facts to 
remember in judging sound-track quality 
is that density has no significance what- 
ever unless the color quality of the ex- 
posing light is rigidly specified. Exami- 
nation of Figs. 2, 3 and 4 clearly indicates 
that merely obtaining a particular den- 
sity on the Kodachrome film does not 
guarantee quality. 

The effects of small variations of color 
quality are shown in Fig. 5. The curve 
marked TOY + 20Y shows per cent inter- 
modulation for film exposed to the 2900 
K tungsten source with filters equal to 
CC-90 Yellow. The series of color bal- 
ances indicates that the color quality 
is reasonably critical and also that the 
low distortion is not the result of con- 
finement of the image to any one layer. 

The choice of an optimum balance for 
variable-area track is less obvious be- 
cause the cross-modulation product is at 
least 40 db below the 400-cycle reference 
level for a considerable range of color 
balances. Additional considerations gov- 
erning the choice of color balance for 
exposing variable-area records are volume 
level, signal-to-noise ratio, frequency re- 
sponse, and exposure latitude. The 
cross-modulation curves of Fig. 6 show 
that the best color balance for variable 
density, obtained with a CC-70Y filter 
in the printing beam, is not the most 
desirable balance for the exposure of 
variable-area records. In this case the 
CC-30M balance provides low distortion 
with the highest usable volume level. 
Again, density alone is not an indication 
that the film has been properly exposed. 

Conclusions 

The color quality of the light which 
exposes the film in the sound-track 
printer controls the potential quality of 
sound reproduction which may be ob- 
tained from Kodachrome sound tracks. 
Density alone is not sufficient to guaran- 
tee that the color film has been properly 



Robert C. Lovick: Sound Tracks on Kodachrome 



85 



uj 10 



TOY + 20Y 



TOY + 20C, 



\ V 



TOY + 20 M 



TOY + 20R 



/TOY + 206 




+20B 



0.4 0.5 0.6 0.7 0.8 

DENSITY (ot 800m?) OF UNMODULATED, UNBIASED AREA 

Fig. 5. Intel-modulation. Effects of small filter changes 
from optimum variable-density balance. 




O.I 0.2 0.3 

DENSITY (ot 800m;/) OF CLEAR AREA 



Fig. 6. Cross modulation. Comparison of best variable-area balance 
with best variable-density balance. 



86 



August 1952 Journal of the SMPTE VoL 59 



exposed. Density is only significant 
when the color quality of the exposing 
light is rigidly specified. 

References 

1. James A. Larsen, "Improved Koda- 
chrome sound quality with supersonic 
bias technique," Jour. SMPTE, 57: 
60-62, July 1951. 

2. John G. Frayne, "Electrical printing," 
Jour. SMPTE, 55: 590-604, Dec. 1950. 

3. John G. Frayne and R. R. Scoville, 
"Analysis and measurement of distor- 
tion in variable-density recording," 
Jour. SMPE, 32: 648-673, June 1939. 

4. J. O. Baker and D. H. Robinson, 
"Modulated high-frequency recording as 
a means of determining conditions for 
optimal processing," Jour. SMPE, 30: 
3-17, Jan. 1938. 

5. R. G. Lovick, "Densitometry of silver 
sulfide sound tracks," Jour. SMPTE, 59: 
89-93, Aug. 1952. 

Discussion 

Anon: I'd like to ask the color temperature 
and the type of photocell used in the play- 
back on all of your test curves? 

Mr. Lovick: The color temperature of the 
lamp used in the reproducer was 2800 K. 
It does make a difference. We use an un- 
filtered Type 868 phototube. 

Anon: It's a cesium cell? 

Mr. Lovick: It's a cesium surface with an 
S-l response. 

H. R. Kossman (Gamer aflex Corp.} : I 
would like to know a little more about the 
filter for the sound printer. Is it a glass 
filter you propose to use there? 

Mr. Lovick: No, we're proposing to use 
the Kodak Color Compensating Filters. 
They are gelatin filters. You have to cool 
these filters if they're tightly enclosed in 
some printers, particularly in contact 
printers. You don't have too much trouble 
in printers such as the Bell & Howell 
Model J. 

Mr. Kossman: You know, we have rather 
confined space there. Of course, they have 
a blower system. . . . 

Mr. Lovick: I realize that in many print- 
ers there is quite a confined space. How- 
ever, you cannot get good sound reproduc- 
tion unless you make some provision for 
using filters of this type to adjust the printer 



light to the color quality that will give you 
the best results. 

Mr. Kossman: I notice that some of the 
labs are using an ultraviolet filter. 

Mr. Lovick: The ultraviolet filter gives 
poorer results than you can expect from the 
color-compensating type of filter. It also 
takes considerably more light. 

F. P. Herrnfeld (Herrnfeld Engineering)'. 
You mentioned a 2-mm heat-absorbing 
glass. Which one do you use? 

Mr. Lovick: We use the Pittsburgh 2043. 

Mr. Herrnfeld: Have you investigated 
single-layer exposures? 

Mr. Lovick: Yes, single-layer and double- 
layer exposures. It's necessary to use pre- 
flash techniques in order to avoid unmodu- 
lated silver sulfide density in the other 
layers. There's some improvement possible 
for variable-density records particularly in 
the exposure latitude. We don't lower the 
minimum distortion but gain in latitude by 
using a Wratten No. 29 filter to preflash the 
bottom layer. There's no particular value 
in trying to remove the middle layer of the 
film. You get improved latitude at the ex- 
pense of the signal-to-noise ratio. 

George Lewin (Signal Corps Photographic 
Center) : Will you tell us how this new 
Kodachrome is going to be distinguished 
from the present type? 

Mr. Lovick: I believe the last of the old 
Kodachrome emulsion is 5265-953. The 
new films are number 1 or later. 

Mr. Lewin: It will not be necessary to 
order it specially? 

Mr. Lovick: No. 

Mr. Lewin: As time progresses, we'll 
start getting the new type? 

Mr. Lovick: The new type will be sup- 
plied as rapidly as possible. 

Mr. Herrnfeld: In your test, how do these 
filters compare with the emulsion pack you 
use for picture printing? 

Mr. Lovick: The filter pack for picture 
printing is a composite pack consisting of 
some cyan, magenta and yellow filters. I 
believe basically it's about 30 cyan, 30 
magenta and 10 yellow. That's based 
again on the 2900 K source that's recom- 
mended for Kodachrome picture printing. 

Mr. Herrnfeld: Have tests been made us- 
ing the picture printing filter pack to print 
the sound track? 



Robert C. Lovick: Sound Tracks on Kodachrome 



87 



Mr. Lovick: The results are poorer than 
those obtained with a properly color- 
compensated sound exposure. The filter 
pack that is used for printing pictures is 
still almost a neutral pack, as far as that 
2900 K source is concerned. There are 
simply enough additional filters available 
so that you can remove some to adjust the 
color quality. 

Mr. Herrnfeld: What was the filter pack 
you mentioned? I mean approximately, 
is it minus the yellow? The reason I am 
asking is that I have made extensive tests 
on other products and I have found that if 
you get a good gray curve from your film, 
in other words that the three emulsions 
give you approximately the same gamma. 



that is where we had the best processing 
quality of sound films. 

Mr. Lovick: That isn't necessarily true. 
Each emulsion was designed for a particular 
dye, irrespective of the amount of halides 
necessary to get that dye. If you convert 
those halides to silver sulfide instead of the 
dye, the curve shapes are no longer similar 
to what they were for the dye deposits. 
There's no reason to believe that they'd 
be similar. The speeds, too, might be quite 
different. Suppose that you have to have 
one and one-half times more halides avail- 
able for the yellow layer than for the other 
layers in order to get sufficient yellow dye 
density. When converted to silver sulfide, 
you would have that much additional con- 
trast in that particular layer. 



88 



August 1952 Journal of the SMPTE Vol. 59 



Densitometry of Silver Sulfide 
Sound Tracks 



By ROBERT C. LOVICK 



Silver sulfide deposits have spectral density characteristics which tend to 
make densitometry less reliable than density measurements of silver deposits. 
Interference filters may be useful in restricting the bandwidth of response of 
electronic densitometers so that densitometry of silver sulfide deposits will 
have increased significance. 



A HE SOUND TRACK on Kodachrome 
film and other multilayer, reversal, color 
films is commonly a deposit of silver 
sulfide. Silver sulfide images are used 
because no satisfactory solution has yet 
been obtained to the problem of pro- 
ducing a good silver image in the sound 
track area and pictures free of silver in 
the adjacent area. 

The curves of Fig. 1 show density as 
a function of wavelength for a silver 
deposit on 16mm Eastman Fine Grain 
Release Positive Film, Type 7302, and 
for a reversal silver sulfide deposit on 
Kodachrome Duplicating Color Film, 
Type 5265. Physical densitometers 
usually have maximum sensitivity in 
the visual region at about 525 m/z. In 
this wavelength region, the major 
errors in the measurement of the density 
of photographically deposited silver are 
the result of the geometry of the instru- 
ment. Differences in spectral response 
of the receptor have practically no 
effect on the calibration of the densitom- 



Presented on April 24, 1952, at the Society's 
Convention at Chicago, 111., by Robert 
C. Lovick, Color Control Div., Eastman 
Kodak Co., Rochester 4, N.Y. 



eter. The accuracy of density deter- 
mination may be adequately stated for 
silver deposits. There is a tendency to 
assume that the same reliability applies 
to silver sulfide deposits. 

The density of silver is minimum at 
525 mju and increases moderately with 
wavelength. The density of silver sulfide 
varies much more with wavelength. 
Assuming equal densities at a wave- 
length of 800 mju, the slope of the spectral 
density curve for silver sulfide is over 
six times greater than the slope of the 
curve for a silver deposit. 

The density of the silver deposit 
measured at 800 mju is 14% greater 
than the density at 525 mju. The density 
of the silver sulfide deposit measured at 
800 mju is only 40% of the density at 
525 m/i. Consequently, silver sulfide 
sound tracks are visually denser than the 
density effective in a reproducer with 
a phototube having an S-l response. 
As a result, reversal silver sulfide sound 
tracks are often seriously overexposed 
in attempts to give them the appearance 
of silver sound tracks. 

Measurements of sound tracks to 
obtain indications of the density effec- 
tive in a reproducer require that heat- 



August 1952 Journal of the SMPTE Vol. 59 



89 




400 



600 800 

WAVELENGTH (millimicrons) 

Fig. 1. Spectral density of silver deposits on Type 7302 
and silver sulfide deposit on Type 5265. 



1000 



3.0 



RMA Wavelength 
Tolerance for 



STANDARD S- I 

EQUAL ENERGY 

RESPONSE 




400 600 800 

WAV E L E N G TH (millimicrons) 
Fig. 2. Standard S-l Phototube response. 



1000 



90 



August 1952 Journal of the SMPTE Vol. 59 



absorbers and other filters be removed 
from the optics of the densitometer and 
that the S-4 phototube be replaced 
with a phototube having an S-l response. 

Wavelength Tolerances 

A standard, equal energy response 
curve of a phototube with an S-l re- 
sponse is shown in Fig. 2. The peak 
sensitivity of a standard tube occurs at 
800 m/z. Such phototubes were not 
designed or ever intended for precise 
photometric measurements. As a con- 
sequence of their general purpose design, 
wavelength tolerance limits of 100 
m/x have been established for the peak 
sensitivity. These limits are entirely 
satisfactory for their general purpose 
service but can produce large differences 
in the measured density of silver sulfide 
sound tracks. 

For the spectrophotometric curve of 
silver sulfide shown and the maximum 
and minimum wavelength tolerances for 
peak sensitivity of the phototube, it has 
been computed that the measured 
density of the sample would be 0.68 
and 1.3 respectively. The potential 
error due to wavelength tolerance alone 
for peak sensitivity of the phototube is 
30%. On a practical basis, this 
error seems to be about 10%. 

Color Temperature Effect 

The output of the phototube is the 
product of the equal energy response 
and the relative energy of the light 
source at every wavelength. The curves 
of Fig. 3 show the product of the stand- 
ard response and the energy of tungsten 
sources at 2500 K and 3000 K. 1 Of 
course, some densitometers may have 
light sources with higher or lower color 
temperatures than these, but this varia- 
tion can introduce a significant error 
in the densitometry of silver sulfide 
deposits. If a standard S-l phototube 
is placed in a densitometer and the color 
temperature of the light source is changed 
from 2500 K to 3000 K, the measured 
density of this sample will change from 



0.90 to 1.02. This is a density dis- 
crepancy of 6%. 

Variations in Spectral Sensitivity 

Another cause of differences in meas- 
urements is the effect of different spectral 
sensitivity for tubes having peak sensi- 
tivities at the same wavelength. From 
a small group of tubes having peak 
sensitivity at the same wavelength, it 
appears that this potential error is of 
the order of 3 or 4%, possibly larger. 

These sources of error are important 
because they are quite large and yet 
may be overlooked in the estimate of 
reliability of densitometry. The tend- 
ency is to assume that because measure- 
ments on a silver deposit in the visual 
region indicate an accuracy of 1 or 2%, 
that measurements on the silver sulfide 
deposit are of the same order of re- 
liability. 

Measurements With Densitometers 
Having Visual Response 

Measurements of silver sulfide sound 
track densities by densitometers with 
phototubes having an S-4 response or 
by visual instruments are much more 
affected by the variation of density with 
wavelength than are measurements with 
instruments having phototubes with S-l 
response. Density measurements, in the 
visual region, of the silver sulfide de- 
posits are more sensitive in detecting 
density variations than are measure- 
ments at 800 mju, but they are consider- 
ably less precise. In addition, sound 
tracks on Kodachrome films have some 
unwanted magenta dye present which, 
although virtually unseen by the usual 
reproducer phototube, will contribute 
significantly to the visual density 
measurement. Visual density measure- 
ments may, therefore, show variations 
which in no way affect sound reproduc- 
tion. The significance of visual measure- 
ments is further reduced by the possi- 
bility that as less silver sulfide is formed, 
more magenta dye will be formed, and 
although the visual density measure- 



Robert C. Lovick: Densitometry of Sulfide Tracks 



91 



S-l RESPONSE 
AT 3000 K 



-I RESPONSE 
AT 2500 K 




600 800 

WAVELENGTH (millim icrons ) 



1000 



Fig. 3. Effect of tungsten light source color temperature change. 



3.0 



1. Interference Filter 

2. Interference Filter plus Wratten 38A 




400 



600 800 

WAVELENGTH (millim icrons) 



1000 



92 



Fig. 4. Spectral density characteristic of one type 
of interference filter. 

August 1952 Journal of the SMPTE Vol. 59 



ment may be only slightly affected, the 
phototube of the usual sound reproducer 
will see a reduced image contrast with 
definite effect on the reproduction of 
sound. 

Measurements of silver sulfide sound 
tracks by densitometers with phototubes 
having S-4 response or by visual instru- 
ments are to be discouraged. 

Standardized Densitometry 

The interchange of useful information 
on sound track printing conditions would 
be greatly facilitated by standardized 
densitometry. The method most likely 
to produce an acceptable degree of 
correlation requires the use of an inter- 
ference filter 2 * 3 to restrict the response of 
the densitometer to a bandwidth of a few 
millimicrons. The density character- 
istics of one type of interference filter 
are shown in Fig. 4. With such a 
filter, the effects of variations of the 
wavelength of peak sensitivity, shift of 
peak due to color temperature of the 
light source, the effects of aging, and 
differences in spectral sensitivity of 
phototubes are virtually eliminated. 
In fact, practically the only sources 
of error that remain are due either to 
the geometry of the instrument or to 
error in the determination of the wave- 
length of peak transmission of the filter. 

The effects of tube responses are 
eliminated so that the same density is 
indicated whether an S-l or S-4 response 
is used. Of course, the sensitivity with 
an S-4 response is so much less that it 
would seldom, if ever, be used. 

The filters are relatively dense so 
that as much as two density ranges 
may be lost. This restricts the choice of 
wavelengths for standardized densitom- 
etry. If 550 m/i were chosen, the 
required unfiltered range for the densitom- 
etry of a sound track on Kodachrome 
film would be to 6, since it would be 
necessary to be able to read to a density 
of about 3.2. However, at 800 mp. 
the unfiltered density range required 
would be only a little more than 3, 



since the maximum density at 800 mju 
of the reversal silver sulfide sound 
track on Kodachrome film is now under 
1.0. 

Acknowledgment 

The author wishes to acknowledge 
the contribution of Jack Pinney and 
Edward Letzer of the Color Control 
Division in obtaining materials and data 
for study of the problems of densitom- 
etry of silver and silver sulfide deposits. 

References 

1. Zworykin and Ramberg, Photoelectricity 
and Its Applications, John Wiley, New 
York, 1949, p. 15. 

2. Bruce H. Billings, "Narrow band 
optical interference filters," Phot. Eng., 
2: 45-52, 1951. 

3. Harry D. Polster, "A symmetrical all- 
dielectric interference filter," /. Opt. 
Soc. Am., 42: 21-23, Jan. 1952. 

Discussion 

John G. Frayne (Westrex Corp.} : I'd like to 
ask if those figures given for density are 
diffuse density? 

Mr. Lovick: They're diffuse. These 
densities are measured on the Western 
Electric RA - 1100B Densitometer modified 
for this purpose. 

Dr. Frayne: With the interference filter 
in the optical system, what density are you 
able to measure with the existing ampli- 
fier? 

Mr. Lovick: We have modified the am- 
plifier so that even with the additional 
filter we still get a density range of 4. 

Dr. Frayne: Is that information going 
to be available? We'd like to know about 
it. 

Mr. Lovick: You mean how to modify 
the amplifier? 

Dr. Frayne: Yes. 

Mr. Lovick: It's only necessary to change 
a few resistors in the preamplifier. 

Dr. Frayne: Even that's worth knowing. 
Are the interference filters available? 

Mr. Lovick: Yes. We've obtained some 
from Bausch & Lomb. The tolerance 
which I think we should require is about 
plus or minus 2 millimicrons in order to 
get good correlation. 



Robert C. Lovick: Densitometry of Sulfide Tracks 



93 



Modulated Air Blast 

for Reducing Film Buckle 



By WILLY BORBERG 



Present-day demands for high-intensity light sources point up the need for a 
suitable technique for reduction of excessive film buckle. Air jets which 
direct a continuous air flow against one or both of the film faces have been 
proposed. This technique does not, however, take into account the cyclical 
nature of film surface deformations during projection. It is found that improved 
performance can be obtained with a modulated air blast which is synchronized 
to the frame cycle. This paper describes the cyclical effects involved and 
shows why the modulated air blast is to be preferred over continuous air blast. 
It presents experimental data regarding buckle magnitudes in 35mm film and 
describes the experimental equipment. 



_L HE TYPE OF BUCKLE with which WC 

are concerned in the present discussion 
is a deformation which takes place during 
the frame cycle while the film is in the 
aperture. It may leave no record of its 
existence on the film after projection. 
It can be made visible by stroboscopic or 
high-speed photographic techniques, ap- 
pearing as a rythmic almost breathing 
motion of the film surface in the aper- 
ture. It produces deterioration of image 
focus during part of the rapidly recurring 
projection cycle. 

The causes of film buckle have been 
investigated and described before. Car- 
ver, Talbot and Loomis, 1 - 2 as well as 
Kolb, 3 have done considerable work on 



Presented on April 25, 1952, at the Society's 
Convention at Chicago, 111., by Willy 
Borberg, General Precision Laboratory, 
Inc., Pleasantville, N.Y. 



the subject in connection with broad 
studies of film performance. They have 
developed the terminology needed for 
presentation and their usage will be 
followed. The present discussion will be 
concerned with those effects which vary 
during the film frame cycle. However, 
a brief statement of the basic factors will 
not be amiss. 

Each single picture frame goes through 
a cycle which starts with pulldown into 
the aperture, proceeds through the first 
exposure, the flicker blade cutoff and the 
second exposure, and ends with the pull- 
down of the next frame. During the two 
exposure intervals the film arrests some 
of the radiant energy from the light 
source and transforms it into heat. This 
causes the film to buckle (or bulge) in a 
manner very similar to that observed in 
the operation of a bimetallic element. 



94 



August 1952 Journal of the SMPTE Vol.59 



The emulsion, being more opaque than 
the base, absorbs energy, expands and 
becomes the outer or convex surface of 
the bulge. The magnitude of the de- 
formation produced varies continuously 
during the frame cycle and by an amount 
which is more than sufficient to affect 
sharpness of image focus. 

The emulsion side of 35mm film is 
toward the light source; and hence the 
film tends to move toward the light, away 
from the lens, while it is in the aperture. 

In accordance with the accepted ter- 
minology, the deformation is called 
negative when the emulsion side is convex, 
and conversely, positive when the emul- 
sion side is concave. Flat film is con- 
sidered to have zero deformation. 

The film upon entering the projector 
gate is not necessarily flat, but may have 
a slightly positive curl, the magnitude of 
which depends to some extent on the age 
and condition of the film. It appears 
that there is some shrinkage of both emul- 
sion and base, the emulsion shrinking 
more than the base, so that the resulting 
curl is slightly positive. Typical posi- 
tive displacement at the center of cold 
35mm film as it enters the gate is between 
zero and 0.010 in. 

Instantly upon registration of the film 
frame with the aperture, the shutter 
uncovers the light for the first exposure 
of the cycle. Light energy is absorbed 
in the emulsion and transformed into 
heat. The expanding emulsion causes 
the exposed portion of the film frame to 
move from its initial zero or positive 
position, shifting it to a negative position, 
and causing it to take a somewhat spheri- 
cal shape. There is a constantly increas- 
ing deformation during the first exposure, 
and a constantly changing distance of the 
emulsion surface with respect to the lens. 
Upon interception of the light by the 
flicker blade, further movement of the 
film surface toward the light source 
comes to a halt. With no light on the 
film, heat absorption by the film cannot 
take place. Instead, there is a loss of 
heat which causes the film to recede 



slightly toward the zero plane. At the 
start of the second exposure, the film 
surface stands somewhere between zero 
and its former maximum negative posi- 
tion. During the second exposure, the 
film continues its excursion negatively, 
first rapidly, then leveling off. At the 
end of this exposure the film reaches a 
more negative position than at the end 
of the first exposure. 

Figure 1 shows the correlation between 
the movement at the center of the film 
surface and particular instants in the 
frame cycle. The same movement oc- 
curs at points off the center of the film 
surface, though to a smaller degree. A 
significant effect which may be noted is 
that the center of the film, which is in 
motion during the entire cycle, travels 
through and beyond the acceptable focus 
limits defined by the depth of the focus 
of the projection lens. 

The projectionist, whose eye just can- 
not follow this rapid sequence of events 
(48 times per second), has to pick a 
"best average focus" position of the pro- 
jection lens, somewhere between the 
maximum positive and maximum nega- 
tive of the two exposure periods. If he 
judges the focus at the center of the 
screen, he picks a "best average focus" 
position near the maximum negative 
buckle of the first exposure. The re- 
maining, earlier part of this exposure pro- 
duces only a poor and undefined image 
on the screen. A portion of the second 
exposure, also, is beyond the limit of good 
image definition on the screen, and good 
optical performance can take place only 
during that part of the exposure in which 
the film displacement line lies within the 
depth-of-focus range. The "best average 
focus" thus obtained gives the best at- 
tainable image at the center of the screen. 
Actually, in practice, the projectionist 
may choose a slightly less negative lens 
position, which is a compromise to gain 
relatively fair overall definition across 
the whole screen. Even this compromise 
results in a fairly large percentage of 
"out-of-focus" time during a cycle. 



Willy Borberg: Reducing Film Buckle 



95 



NEXT 



DEPTH OF 

FOCUS 
"RANGE 
OF LENS 




Fig. 1. Film displacement due to buckling at center of frame No Air. 




Fig. 2. Test equipment used to determine film buckle magnitudes and time relations, 
96 August 1952 Journal of the SMPTE Vol. 59 



For the conditions demonstrated in Fig. 
1, good optical performance is attained 
during only about 40% of the first ex- 
posure and 60% of the second exposure, 
or a total of only 50% during a complete 
frame cycle. This is the best the pro- 
jectionist can do. 

The figures so far presented demon- 
strate the magnitude of the defect with 
which we are concerned, since they have 
been obtained with representative equip- 
ment, operating under conditions which 
might be found in any large theater. 
For test purposes, the projector was fitted 
with facilities to determine the various 
focus positions of the 5-in. focal length 
f/\ .9 projection lens. 

The light source was a Hi-Candescent 
Arc Lamp, with F-2 condensers, burning 
at 160 amp and delivering about 9000 
1m to the screen with the shutter running. 

All focus settings were made with the 
aid of Simplex Screen Scopes. The 8- 
power magnification thus provided en- 
abled lens adjustment with greater pre- 
cision than could have been attained by 
direct observation of the screen from the 
projector. 

The film plane position along the op- 
tical axis was measured directly in terms 
of lens displacement, a dial indicator cali- 
brated in thousandths of an inch being 
affixed to the lens mount for this purpose. 
Initial calibration for zero position on 
the dial indicator was made by focusing 
the lens to produce a critically sharp 
image of a conical hole in a flat steel 
plate, the small end of the hole being in 
the same plane as the emulsion contacting 
surfaces of the film trap. Up to this 
point, the method and equipment are 
essentially the same as those employed 
and described by Kolb. 3 

The addition of a viewing shutter to 
the equipment enabled observation of 
successive phases of the cyclicly varying 
film frame motion (see Fig. 2). The 
viewing shutter's drive-motor stator was 
rotatable so that the shutter opening of 
about 9 could be phased with relation 
to the synchronously running projector. 



This stroboscopic arrangement made it 
possible to view the screen image in 
small time increments of about 1 msec 
through all exposure phases of successive 
frame cycles. The film emulsion position 
during any specific phase of the exposure 
periods could thus be established with- 
out regard to possible out-of-focus condi- 
tions during the remaining unobserved 
portions of the cycle. Dial indicator 
readings were then recorded in relation 
to the phase settings. A contactor on the 
projector shutter timed a short-duration 
light flash for establishing correct phase 
reference. 

The equipment as described permitted 
studies of film behavior under actual 
operating conditions. 

The technique of air-blast cooling of 
film, by which opposing air forces of the 
front and rear jets are adjusted so as to 
produce a force for positioning the film, 
was found to be at best a partial solution 
to the problem. It is possible to move 
the film by this method and to shift the 
average focus position; the resultant 
force, however, acts upon the film con- 
tinuously, and therefore, cannot correct 
for the intermittent cyclical frame de- 
formations caused by the internal buck- 
ling forces in the film which occur during 
the two exposure periods. 

The center of each frame travels over 
a range of about 0.020 or 0.030 in. This 
range is not greatly reduced by applica- 
tion of a continuous displacing air force 
(Fig. 3). The continuous jets produce a 
shift in average focus position; this, by 
itself, only slightly alters the ratio of 
"in focus" and "out-of-focus" intervals. 
The air serves primarily as a cooling 
agent, preventing possible damage to the 
film in the form of embossing or blister- 
ing or the formation of permanent buckle. 

It was felt that, because of the cyclical 
nature of the film frame deformations 
involved, any corrective action to neu- 
tralize the defects should be similarly 
cyclical. Hence, the following approach 
(Figure 4) was tried: 



Willy Borberg: Reducing Film Buckle 



97 



NEXT 



CONTINUOUS AIR FROM FRONT JE1 



DEPTH OF 
FOCUS 
RANGE 
OF LENS 




I 1 



f I f 1 I 



CONTINUOUS AIR FROM REAR JET 
Fig. 3. Film displacement due to buckling at center of frame Continuous Air. 



(a) The air from the front jet was 
modulated by means of a rotary valve 
driven from the shutter shaft. 

(b) The air from the rear jet was not 
modulated and the steady stream of air 
from this jet was used to force the film 
toward the lens, thus partly neutralizing 
the internal forces, which tend to make 
the film take a deep negative buckle 
under the influence of light. 

(c) The correcting air pulses from the 
joint jet were timed so that the resultant 
forces from both front and rear jets op- 
posed the cyclicly varying buckle forces. 
The motion of each film frame on the op- 
tical axis could thus be controlled. 

Figure 5 illustrates the timing of the 
jets and shows that the position of the 
film frame can be held steady within 
fairly close limits. It should be noted 
that the excursions of the film frame sur- 
face can be confined to the depth-of- 
focus range of the lens. Good optical 



performance is thus attained over vir- 
tually the entire frame cycle. 

Figure 5 also shows that a negative 
displacement of approximately 0.012 in. 
is allowed to exist at the center of the 
frame. The question may be asked, 
"Why is the process not carried beyond 
this point so as to bring the displacement 
to zero?" There are two reasons for not 
doing so. The first, as pointed out by 
Kolb, is concerned with the performance 
of the projection lens. In most projec- 
tion lenses the focal plane of field is not 
truly a plane, but rather a curved surface. 
For best performance in this respect, the 
film is allowed to approximate this sur- 
face. The second reason is that flat film 
seems to be somewhat flaccid under the 
influence of air flow, as compared to film 
which is bowed to even a slight degree. 

Since the film can be kept within the 
depth-of-focus limit of the projection lens 
during nearly the entire time of the two 



98 



August 1952 Journal of the SMPTE Vol. 59 






ROTORY VALVE 
DRIVEN FROM 
SHUTTER SHAFT 



FEED SPROCKET 




FILM DISPLACEMENT 
INDICATOR 



INTERMITTENT ^/^"^N 
SPROCKET J Q 

>^> 



FOCUS KNOB 



( 



Fig. 4. Arrangement of air jets and film displacement indicator. 




DEPTH OF 
_ FOCUS 
RANGE 
OF LENS 



CONTINUOUS AIR FROM REAR JET 
Fig. 5. Film displacement due to buckling at center of frame Pulsed Air. 



Willy Borberg: Reducing Film Buckle 



99 



exposure periods, there is marked im- 
provement in screen image definition. 

Experiments so far have been directed 
toward the use of the modulated front 
jet. It is quite possible to use the oppo- 
site arrangement of a steady front jet 
and pulsed rear jet. For better cooling, 
however, it seems advisable to let the 
continuous air stream wash the emulsion 
side of the film, relying on the front jet 
as the position correcting agent. A 
pulsed combination of both jets may 
offer some advantages in air economy, but 
has not been tried. 

References 

1. E. K. Carver, R. H. Talbot and H. A. 
Loomis, "Effects of high-intensity arcs 
upon 35mm film projection," Jour. 
SMPE, 41: 69-87, July 1943. 

2. E. K. Carver, R. H. Talbot and H. A. 
Loomis, "Film distortions and their 
effect upon projection quality," Jour. 
SMPE, 47: 88-93, July 1943. 

3. F. J. Kolb, Jr., "Air cooling of motion 
picture film for high screen illumination," 
Jour. SMPE, 53: 635-664, Dec. 1949. 

Discussion 

R. T. Van Niman (RCA Victor Div.) : I 
perhaps missed something in the early part 



of the talk, but did you consider whether or 
not the amount of deformation varies with 
the type of picture material? I believe 
Mr. Kolb pointed out that the amount of 
buckling depends to some extent upon the 
density of the film in the aperture at that 
time. 

Mr. Borberg: Yes, it does matter, but 
there is always deformation, even with a 
very low density. The worst condition 
occurs with a dark film, and necessarily the 
amount of buckle depends also on the 
energy of the light source. 

Mr. Van Niman: No attempt has been 
made to compensate for the variation in 
density along the film then? 

Mr. Borberg: No. A photocell device 
operating from screen illumination to con- 
trol air blast has been considered. Such a 
device would compensate for scene-to-scene 
variations which are beyond the projec- 
tionists' ability to follow, but the instru- 
mentation just hasn't gone that far. 

W. W. Lazier (National Carbon Co.}: 
Does the intermittent air blast make much 
audible noise? 

Mr. Borberg: Yes, there is some noise, 
but it's not very disturbing and it does not 
exceed the noise of jets with continuous air. 
There is a purring noise, I might say. 



100 



August 1952 Journal of the SMPTE Vol. 59 



A Method of Direct- Positive Variable-Density 
Recording With the Light Valve 



By O. L. DUPY 



In this system the light valve is placed in the cathode circuit of a nonlinear 
amplifier, the nonlinearity being of such a nature that the relation between 
the input to the amplifier and the transmission of the developed film is linear 
over a large percentage of the film-transmission range. The method of de- 
termining the shape of the necessary nonlinearity and how it is produced is 
described. 



M 



.AGNETIC FILM has proved to be an 
excellent medium for sound recording in 
the motion picture industry. However, 
considering the well-established editing 
techniques and the existing editing and 
viewing equipment, it will be some time 
before the magnetic record will replace 
the photographic sound record for use 
throughout the studio. The economical 
method of obtaining this record is to 
transfer the sound electrically from the 
magnetic record to a film that has the 
characteristics of a print when developed. 
The making of direct-positive prints 
by electrical printing has several ad- 
vantages. The most important is the 
saving of the negative film and the cost 
of the development and printing of this 
film. Also, the reduction of the time 
that elapses between the recording and 

Presented on April 25, 1952, at the Society's 
Convention at Chicago, 111., by John G. 
Frayne for the author, O. L. Dupy, Metro- 
Goldwyn-Mayer Sound Dept., Culver City, 
Calif. 



the delivery of a print is sometimes of 
great importance. Another advantage 
is the reduction of the film background 
noise by the elimination of the film noise, 
inherent in the negative, which is added 
to the print. Another advantage is the 
elimination of the flutter introduced by 
the printer, which is generally the con- 
tributor of a good percentage of the total 
flutter in film recording. 

The main disadvantage in obtaining a 
linear recording from a variable-density 
type of photographic characteristic is the 
rather elaborate amplifier system re- 
quired to offset this distortion, but one or 
possibly two such units will handle all 
the daily printing for a large studio. 
The push-pull variable-area method of 
recording has been successfully adapted 
to produce these direct-positive prints.* 
With the push-pull system a higher track 



*L. I. Carey and Frank Moran, "Push-pull 
direct-positive recording an auxiliary to 
magnetic recording," Jour. SMPTE, 58: 
67-70, Jan. 1952. 



August 1952 Journal of the SMPTE Vol. 59 



101 



80 



70 



60 

in 

150 
n 



I- 40 

2 



30 



10 



\ 



50 100 150 

EXPOSURE C CATHODE CURRENT ) 

Fig. 1. Film-recording characteristic. 



200 



200 



RESULT 




12 



102 



Fig. 2. Correcting nonlinear amplifier characteristic. 
August 1952 Journal of the SMPTE Vol. 59 



density than normal can be employed 
because of the cancellation of the cross- 
modulation products in push-pull re- 
production, thus producing results that 
equal the cancellation achieved by the 
normal negative and print process. The 
nonlinear exposure versus light-trans- 
mission characteristics of the film enters 
into the problem of making a variable- 
density direct-positive. In order to de- 
termine the nonlinear characteristics, 
samples were exposed by sending direct 
current in fixed steps through the light 
valve in a standard recording machine. 
These strips were processed using the 
M-G-M standard release development 
procedure. The resulting strips were 
measured by inserting a 400-cycle chop- 
per in the light beam of a standard film- 
reproducing machine and measuring the 
audio signal at the output of the photo- 
electric cell amplifier. By this pro- 
cedure, the test included all the variables 
encountered in the recording and re- 
producing systems. 

The resulting characteristic is shown 
in Fig. 1 . The above tests were repeated 
over a period of time in order to check 
the stability of the variables involved. 
The results proved that this method of 
making a variable-density direct-positive 
was practical. 

Figure 2 shows the schematic of an 
amplifier, the characteristics of which are 
the reciprocal of Fig. 1 . The first stage 
of the amplifier has a practically linear 
characteristic and is used as a voltage 
amplifier directly coupled to the second 
and third stages or sections. The noise- 
reduction control voltage is fed to the in- 
put grid in series with the secondary 
winding of the input transformer. The 
second stage controls the shaping of the 
middle and upper end of the curve by 
being biased negative almost to cutoff; 
the signal received from the cathode re- 
sistance of the first stage is such that it is 
linear for the lower half of the range, and 
becomes nonlinear as the driving signal 
increases. The third stage controls the 
shaping of the extreme upper end of the 



curve. This is accomplished by biasing 
the grids negative beyond cutoff and 
driving them with a signal voltage that 
will cause the tubes to conduct only on 
the positive peaks of the signal. 

Figure 3 shows the method of obtain- 
ing this curvature by using a number of 
tubes in parallel, the grids of which are 
biased to operate at various points in the 
nonlinear portion of their grid volts 
versus plate-current curves. The over- 
all shape is obtained by adjusting the 
balance between the grid and signal 
voltage, and the number of tubes used. 

The light valve must be directly 
coupled to this amplifier because the re- 
sulting distorted signal is composed of 
direct current; the signal fundamental 
and a large amount of harmonics of the 
signal, and in addition the noise-reduc- 
tion signal must be altered by this circuit. 

Figure 3 shows the contributions of all 
three stages and the overall character- 
istic of the nonlinear amplifier. A 
Western Electric RA-1238, 200-mil push- 
pull variable-density light valve was used 
in these studies and in recording the 
demonstration film which was run at the 
close of the paper. It is necessary to 
employ one amplifier of the type shown 
in Fig. 2 for each component of the push- 
pull valve. This results in a classical 
type of push-pull reproduction, and a 
higher degree of an overall linearity is 
obtained than when using a standard 
single track. However, good quality is 
obtained from a single track provided 
care is taken in the setting of the operat- 
ing parameters. 

A direct current is applied to the light 
valve, in opposition to the cathode cur- 
rent, for adjusting the static opening of 
the valve for zero signal input. A noise- 
reduction bias current is applied to each 
component of the light valve through its 
associated amplifier. Since the resulting 
sound track is in effect a positive, the 
ribbons are either mechanically or elec- 
trically biased open, rather than closed 
as in a normal negative-positive record- 
ing. The action of the input noise- 



O. L. Dupy: Direct-Positive Variable-Density Recording 



103 




104 



August 1952 Journal of the SMPTE Vol. 59 



30 

QC 



20 




300 200 100 100 200 300 '400 500 
VALVE CURRENT 

Fig. 4. Predistortion curve for extended range recording. 



reduction voltage then serves to cancel 
this d-c bias, the minimum spacing of 
the ribbon being obtained for maximum 
signal input. Experience has shown 
that noise reduction equivalent to that 
obtained in ordinary recording can be 
obtained in this method of recording. 

The shape of the correcting curve was 
checked by recording signals at various 
levels and measuring the distortion. 
The part of the curve that was incorrect 
was found by measuring the distortion of 
a low-level signal that was moved in 
steps, over the complete range of the 
characteristic, by independently varying 
the noise-reduction control voltage. 
This information was used for final in- 



dividual adjustment of each section of 
the amplifier. 

It should be noted that the current 
required from the B supply varies at both 
the signal envelope and audiofrequency 
rates. A regulated B voltage supply 
having a rapid recovery rate and a low 
internal impedance of about 0.9 ohms was 
satisfactory. The necessary mainte- 
nance, checking and adjustments have 
been reduced to a routine. We antici- 
pate that experience will produce a sys- 
tem with better uniformity and quality 
than the negative and positive system. 

Having developed a nonlinear system 
with adjustable characteristics, we have 
adapted it to extend the volume range 
of the print made from a standard nega- 



O. L. Dupy: Direct-Positive Variable-Density Recording 



105 



tive variable-density recording. This 
is done by making the amplifier linear 
over the corresponding linear film- 
transmission range and then nonlinear 
in the direction necessary to correct the 
film curvature in the high transmission 
range. The maximum volume output 
has been increased by approximately 6 
db. Figure 4 shows a typical overall 
negative-positive exposure versus trans- 
mission curve, and illustrates the distor- 
tion that occurs when attempting to use 
the full transmission range of the film. 



Figure 4 also shows how by distorting the 
input signal a sine-wave result can be 
produced that extends over the trans- 
mission range from 5 to 80%. 

M-G-M has used the direct-positive 
system described in this paper for several 
months experimentally to make tempo- 
rary recordings for previews and in other 
intrastudio operations. The sound qual- 
ity has proved to be invariably satis- 
factory indicating that this method of 
transferring from magnetic originals to 
direct-positive density is quite feasible. 



106 



August 1952 Journal of the SMPTE Vol. 59 



International Auxiliary Language 
for Motion Pictures 



Before reading the article by Otto C. 
Bixler beginning on page 109, please 
read the page of Interlingua translation 
immediately following this and see how 
much of it you can understand at sight. 

Interlingua is the nearest attainment 
of a workable international language for 
the contemporary world which modern 
linguistic science can produce. This is 
the claim of the International Auxiliary 
Language Association (I ALA) as the 
result of many years of research on one 
of the most timely problems of communi- 
cation. lALA's research was set up by- 
noted linguists in Europe and the United 
States and has been carried out by a 
staff of experts in different languages. 

lALA's staff has devised a system for 
screening off words which are inter- 
nationally known and for giving them 
standardized forms and definitions. Some 
27,000 of them are presented in the 
Interlingua-English Dictionary. A simple 
grammar employing only those features 
which languages have in common has 
been prepared to operate this natural 
international vocabulary. 

Interlingua includes general and tech- 



This presentation has been prepared 
through the kindly offices of Dr. Alfred N. 
Goldsmith. This brief description of In- 
terlingua has been prepared by Mary 
Bray, and Dr. Alexander Code has trans- 
lated into Interlingua the page immediately 
following. Both are staff members of the 
International Auxiliary Language As- 
sociation. 



nical words of every type. Words from 
the Romance languages dominate the 
general vocabulary. The technical 
terms drawn directly from Latin and 
Greek are in the majority for the reason 
that the international world of science 
and technology is constantly creating its 
own international language. 

While Interlingua is basically a West- 
ern language it does not exclude any 
Oriental words in international circula- 
tion. 

An auxiliary language to supplement 
mother tongues should represent as 
many national languages as possible. 
Interlingua has the psychological asset of 
looking familiar to a world of readers 
comprising North America, South 
America, Europe, and readers in Asia 
and Africa who know one of the Euro- 
pean languages. 

IALA is bringing Interlingua to the 
attention of groups of scientists and tech- 
nologists. The Association will welcome 
suggestions and comments from readers 
of the Journal of the SMPTE as to possible 
collaboration with engineering groups 
at the heart of the motion picture indus- 
try. The eventual use of Interlingua in 
export-film captions is not beyond prac- 
tical imagination in the development of 
world markets. 

Alfred N. Goldsmith, Past-President 
of the SMPTE, has been a member of the 
Board of Directors of IALA since its 
founding. The headquarters of IALA 
are at 420 Lexington Ave., New York 17, 
N.Y. 



August 1952 Journal of the SMPTE Vol. 59 



107 



Un commercial phonoregistrator binaural 



Per OTTO C. BIXLER 



Le disveloppamento hodierne del apparatura de phonoreproduction es multo 
avantiate. Proque le avantages del registration stereophonic ha previe- 
mente essite demonstrate, nos ha credite que le proxime desiderato re appara- 
tura s commercial esserea le fabrication a precio rationabile de un sy sterna 
binaural. Nos presenta hie un revista del factores theoric implicite in binaural 
phonoregistration e reproduction, insimul con un description del apparatura 
technic disveloppate pro satisfacer le requirimento de alte qualitate acustic 
intra le limites de rationabile costos total. Nos describe alicun nove problemas 
e effectos incontrate in iste programma de disveloppamento. 



Desiderates structural del apparatura 
binaural 

Le decision a preparar pro uso com- 
mercial un binaural registrator a banda 
resultava del desiro de suppler phono- 
registrantes con ameliorate e nove 
methodos de presentation. Esseva pren- 
dite in consideration le facto que usque 
nunc nulle binaural apparatura ver- 
mente commercial ha essite presentate al 
publico ben que numerose firmas (inter 
illos Bell Laboratories, Fox Studios, 
Warner Bros., e alteres) ha facite multo 
satisfactori demonstrationes stereophonic. 
Post le qualitate de phonoreproduction 
habeva essite avantiate a su presente alte 
fidelitate con excellente responsas a 
frequentia, minimal cambiamentos de 
phase e bon reproduction transiente, on 
recognosceva que alique, nonobstante, 
mancava. Iste "alique" es le distribu- 
tion spatial del sono original. Le repro- 
duction monaural del sono emanante de 



Presentate le 24 de april, 1952, al conven- 
tion del Societate a Chicago, 111., per Otto 
C. Bixler del firma Magnecord, Inc., 225 
W. Ohio St., Chicago 10, 111. 



multiple fontes a disposition spatial in- 
troduce distortiones spatial. Le optime 
methodo a eliminar tal distortion es re- 
producer sonos stereophonicamente. Ver 
stereoreproduction de sonos es technica- 
mente satis difficile e relativemente cos- 
tose. Le secunde optime methodo es le 
binaural phonoregistration e reproduc- 
tion. De facto, sonos binaural repro- 
ducite per medio de receptores auricular 
resulta pro le auditor in un quasi per- 
fecte recreation del phonoimpacto origi- 
nal. 

Theoria de audition binaural 

In principio, le factores theoric del 
phonopresentation binaural visa a pro- 
ducer, a un plus tarde tempore, le mesme 
amplitude de sono e relation de phases in 
cata un del duo aures del auditor como si 
ille habeva essite originalmente presente. 
On debe notar que le aures e le cerebro 
del auditor constitue un systema de com- 
putation directional basate super lor 
sensitivitate a phases e amplitudes. Iste 
systema dual involve un area intersec- 
tional de "sensitivitate contra frequen- 
tia" que es determinate sequentemente: 



108 



August 1952 Journal of the SMPTE Vol. 59 



A Commercial Binaural Recorder 



By OTTO C. BIXLER 



Present-day sound recording-reproducing equipment is at a very high state 
of development and, since the benefits of stereophonic recording have been 
previously demonstrated, it was believed that the next desirable step in 
commercial equipment would be the manufacture of a reasonably priced 
binaural system. A review of the theoretical factors involved in binaural 
sound recording and reproduction is presented along with a description of 
the technical equipment developed to fill the needs of high-quality binaural 
sound consistent with a reasonable overall equipment cost. Some novel 
problems and effects experienced in this development program are described. 



Binaural Equipment Design Objective 

The decision to design a commercial 
binaural tape recorder was based upon 
the desire to provide the recording field 
with an enhanced, novel method of 
sound presentation. Consideration was 
given to the fact that to date no true 
commercial binaural equipment had 
been presented to the public although 
many concerns, including Bell Labora- 
tories, Fox Studios, Warner Bros., and 
others, have given highly satisfactory 
public demonstrations of stereophonic 
sound. After the quality of sound 
reproduction was brought to its present 
high fidelity with excellent frequency 
response, minimum phase shift and good 
transient reproduction, it was realized 
that something was still lacking. That 
something is the normal spatial dis- 
tribution of original sound. Monaural 
reproduction of a spatially disposed 

Presented on April 24, 1952, at the Society's 
Convention at Chicago, 111., by Otto C. 
Bixler, Magnecord, Inc., 225 West Ohio 
St., Chicago 10, 111. 



multiple sound source introduces spatial 
distortion. The best way to eliminate 
this distortion is to reproduce sound in a 
stereophonic manner. True stereo- 
sound is quite difficult of technical 
achievement and is comparatively costly. 
The next best method is the use of 
binaurally recorded and reproduced 
sound. As a matter of fact, when bin- 
aural sound is reproduced through 
earphones an almost perfect re-creation 
of the original sound impact upon a 
listener is obtained. 

Binaural Hearing Theory 

Basically, the theoretical factors in- 
volved in binaural sound presentation 
are aimed at producing, at a later time, 
the same sound amplitude and phase 
relationship in each of a listener's two 
ears as if he had been present originally. 
It is to be noted that a listener's ears 
and brain constitute a directional com- 
puting system based upon their phase 
and amplitude sensitivity. This dual 
system has a sensitivity-versus-frequency 
crossover area determined as follows: 



August 1952 Journal of the SMPTE Vol. 59 



109 







Fig. 1. High frequencies pass by an observer's far ear. Low frequencies readily 
curve around the cranial obstruction to the far ear. 



The average human-ear phase-sensi- 
tivity range is from some very low fre- 
quency up to approximately 800 to 
1000 cycles/sec, which thus allows a 
perception of directivity by binaural 
phase comparison over this range. The 
amplitude sensitivity range of the indi- 
vidual ear is from the lowest frequency 
perception point up to the highest fre- 
quency perception limit within the 
dynamic volume range of the ear. This 
dynamic volume range is defined by the 
standard Fletcher-Munson hearing 
curves modified by the room masking 
noise level. 1 

By simple amplitude comparison a 
mental computation of directivity may 
be obtained, except as limited by the 
physics of sound propagation. This 
means that due to the lack of directivity 
of low-frequency sounds below, say, 800 
to 1000 cycles, the ear's amplitude- 
detection ability is of no avail, since a 



low-frequency sound wave curves around 
the head without appreciable amplitude 
loss. Therefore, the amplitude-derived 
directional sensitivity of the binaural 
ear arrangement falls off rapidly. This 
is exemplified by the fact that a 1000- 
cycle/sec tone directed toward a listener 
from one side of his head produces only 
a 3-db level difference at his far ear 
compared with the near ear; a 10,000- 
cycle/sec tone under the same condi- 
tions produces a 30-db level difference 
(Fig. 1). 

It may be shown that the portion of 
normal auditory perspective due to 
phase sensitivity is related to the lineal 
distance between the human ears. Let 
us assume that a theoretical observer 
has a between-the-ears distance of, say, 
6.78 in. Under certain environmental 
conditions the speed of sound in air is, 
say, 1130 ft/sec. The maximum fre- 
quency, /, that the ears may compare 



110 



August 1952 Journal of the SMPTE Vol. 59 



phase on, has a half wavelength, X/2, 
equal to the distance between the ears 
(Fig. 1). Therefore, if: 

11 SO 
X = 6.78 X 2/12; then/ = - = 

A 

1130 



7S212 

That is, the maximum possible frequency 
for binaural phase detection by this 
theoretical observer is in the order of 
1000 cycles/sec or less. 

Most speech sound sources possess 
frequencies both above and below the 
crossover frequency range of from 800 
to 1000 cycles. Not only does this 
enable the observer to compare angular 
location by both phase and amplitude 
methods (and to derive a more accurate 
location), but since phase shift of a given 
frequency is a function of both angular 
position as well as distance, it provides 
a measure of the distance to the sound 
source. 

In addition to the localization system 
defined by the base distance between 
the ears and the mental computation 
of angles, the mind has an additional 
distance-computing ability based upon 
the ratio of direct sound to reverberant 
sound impinging upon the eardrum. 

Microphone Placement 

In view of the above, it becomes 
immediately apparent that in order to 
record binaurally for later binaural 
reproduction some care should be 
exercised in microphone placement. 

The first basic principle underlying 
microphone placement is that the 
perpendicular bisector of the line joining 
the pickup microphones represents the 
center line of a fictional listener's posi- 
tion. During reproduction, the loud- 
speaker placement should be such that 
the perpendicular bisector of the line 
joining the loudspeakers coincides with 
the real listener's center line. This 
arrangement results in both depth and 
lateral stereophonic "image" location, 
dependent upon both phase and the 



intensity ratio of the direct sound picked 
up by the two microphones. 

The second principle underlying 
microphone placement affects the ap- 
parent position of the sound behind the 
immediate foreground. The distance 
of the source from a single microphone 
is also determined mentally by a com- 
parison of the reverberant sound to the 
direct sound. The most accurate mental 
calculation is made when this ratio is 
not in the extremes. Therefore, both 
exceedingly close and overly distant 
microphone placements are to be 
avoided. 

Under a strict binaural microphone 
arrangement the two microphones should 
be relatively close together and have 
individual pickup patterns approxi- 
mating those of the human ear; the 
placing of an acoustic septum between 
the microphones would be desirable. 
Under an expanded arrangement, where- 
in a simple stereophonic system is ob- 
tained, the microphones are spaced 
quite widely apart and a third micro- 
phone with isolation amplifiers and 
attenuators is added midway between 
these two primary microphones. The 
object of the center microphone is to 
feed a small amount of sound energy 
to both recording channels and thereby 
to correct for the spatial distortion 
occasioned by moving the primary 
microphones apart. 4 Unless this cor- 
rection is made, some depth location 
error occurs, especially in the area 
midway between the primary micro- 
phones. If some depth location error 
may be permitted, which it may be if 
the sound is not associated with a con- 
current motion picture, then it is readily 
possible to omit the center microphone. 

Binaural Presence Listening 

The physiological sense satisfaction 
that yields the psychological impression 
of being present in a nonexistent room is 
the startling factor in listening to a 
binaural recording for the first time. 
The sense of "presence" obtained is 



Otto C. Bixler: Binaural Recorder 



111 



considerably different from the normal 
usage of this word. In accepted sound 
practice the reproduction objective is 
to bring the sound source into the 
presence of the listener. Listening to a 
binaural recording can best be de- 
scribed as literally taking the listener 
into the presence of the scene where 
the original recording was made. 

This effect of realism is particularly 
effective when listening with headphones. 
When considering theoretical factors it 
would not seem that loudspeaker listen- 
ing would be very effective for binuaral 
reproduction. However, listening tests 
readily convince one that considerable 
enhancement is still retained with 
speakers although not of such a high 
order as that of earphone listening. The 
use of earphones prevents a listener 
from turning his head to aid in localizing 
sound sources; loudspeaker reproduction 
on the other hand allows a listener to 
retain this mechanical aid to localiza- 
tion. Loudspeaker placement is of con- 
siderable importance in good reproduc- 
tion. The use of too large or too "live" 
a room or too great a listener distance 
greatly reduces the effectiveness of 
binaural loudspeaker reproduction. 

Random Noise Correlation 

An unexpected effect was noted when 
some rather poor recordings were un- 
intentionally made and then played 
back. When the recording medium or 
equipment random-noise level is high 
with respect to the level of the recorded 
signal a unique result ensues. The 
random nature of this white noise is 
such that it allows false phase and 
amplitude coincidence to be correlated 
by the brain to produce apparently 
localized sources of noise. The localiza- 
tion means focused listening attention; 
the effect thus results in raising of ap- 
parent loudness of discreet noise "pulses." 
Since these pulses are strictly random 
mental correlations, their number is 
far less than the actual number of white 
noise "pulses"; therefore, the net effect 



is a coarsening and apparent increase 
of the background noise level to the 
listener. Practically speaking, this 
means that binaural recordings made 
for maximum music appreciation should 
be made with particular care toward 
maintaining the best overall measured 
signal-to-noise ratio. 

The Tape Transport 

The development of the binaural 
tape transport from a standard recorder 
was very desirable in order to keep 
manufacturing costs down and allow 
sales at a reasonable price to the cus- 
tomer without the necessity for designing 
a new special unit with its attendant 
reflected high sales price. It was found 
possible to extend the development of a 
standard Magnecord PT63-A tape trans- 
port mechanism for use in a binaural 
recording system. This basic tape trans- 
port mechanism possesses an assembly 
incorporating three heads. The tape 
passes in succession over, first, the erase 
head, then, the normal recording head, 
and, thence, over the tape monitor head 
before it is pulled by the capstan and 
fed to the take-up reel. 

Consideration was given to the possi- 
bility of retaining the tape monitor 
feature for the binaural system. How- 
ever, it was determined that the addi- 
tional system complexity would add 
materially to equipment size and costs 
because of the immediate requirement 
for two monitor heads and two amplifier 
monitoring channels as well as extra 
controls. The mechanical layout of 
the front panel of the existing PT63-A 
tape transport unit would also be 
unduly complicated by the addition of 
the two extra magnetic heads required. 
It was, therefore, decided that the 
normal full-track record head would be 
replaced by a half-track record head 
and the position normally occupied by 
the monitor head would be used for a 
second half-track record head for the 
other half of the tape. 



112 



August 1952 Journal of the SMPTE Vol. 59 



It is of interest to note that in this 
standard unit the erase head forms the 
principal load for the 60-kc erase and 
bias oscillator with the record head bias 
coil being a relatively small series 
impedance in the circuit. It was 
therefore possible to add the bias 
winding for the second recording head 
in series with the existing erase and 
record heads without any appreciable 
net change in bias or erase currents. 
Using the above-described arrangement 
it was then only necessary to supply 
proper pole pieces, and to reconnect the 
internal wiring to the heads to accom- 
modate the second recording channel. 
Plug and receptacle arrangements are 
so chosen as to automatically maintain 
channel identity in the interunit cables. 

With the exception of the nameplate, 
there is no apparent difference between 
a binaural Magnecorder and a normal 
single-track unit unless the magnetic 
head covers are lifted to allow a view 
of the half-track pole pieces which do 
the recording. The half-track pole 
piece consists simply of a normal full- 
track pole piece with approximately 
^ of the Mu-metal cut away and a brass 
insert soldered into its place in order to 
fully support the tape. 

The Amplifier Unit 

The development of a binaural re- 
cording and reproducing amplifier was 
essentially a specialized packaging job 
which involved building a new portable 
dual amplifier unit, each amplifier 
having all the characteristics of existing 
unit standard amplifiers. The packag- 
ing was accomplished with only a minor 
increase in space and weight for the dual 
amplifiers over that required by a similar 
existing single-channel amplifier. The 
latest techniques in the use of miniature 
tubes and components were employed 
in the manufacture of this equipment. 
Individual illuminated VU (Volume 
Unit) meters were provided for each 
recording and reproducing channel as 
well as individual gain controls. 



A unique problem in the design of this 
unit arose due to the necessity for pro- 
viding an overall or master gain control 
which controlled simultaneously the 
gain of both channels. This was ac- 
complished through the use of a special 
dual potentiometer with matched rota- 
tional ohmic accuracy in the order of 
plus or minus 5%. 

Provision was made for headphone 
monitoring from the front panel of the 
amplifier through the use of specially 
built Permoflux binaural headphones 
having an effective response to over 
12,000 cycles/sec. These headphones 
are provided with large foam-rubber 
ear cushions in order to exclude ex- 
traneous noise and to reduce the well- 
known head fatigue that comes from 
the use of ordinary earphones. Dual 
monitor speakers close together on a 
small panel would not yield any useful 
binaural effect and might be dangerously 
confusing for monitoring use. There- 
fore, in addition to the binaural head- 
phones, a single small monitor speaker 
is provided behind a flocked screen 
panel on the front of the amplifier. A 
unique control is included for this 
speaker which is so arranged that it is 
"off" when set at its center position. 
Maximum volume for one channel is 
obtained by turning the control to the 
extreme right, and maximum volume 
for the other channel, by turning the 
control to the extreme left. 

The amplifier tube lineup for a single 
amplifier channel consists of two 5879 
tubes followed by a dual triode 12AX7, 
the second half of which is used as an 
inverter driving a pair of push-pull 
6AQ5 tubes. The same amplifier is 
used for playback as well as recording. 
A multiple section (shielded between 
sections) ganged selector switch is used 
to switch equalizer and gain functions 
for the dual amplifiers when changing 
from the record to playback positions. 
In order to provide freedom from hum 
in the low-level stages of the amplifiers, 
direct current is used on the filaments of 



Otto C. Bixler: Binaural Recorder 



113 



BlNAURAL RECORD - PLAY BACK 
FREQUENCY RESPONSE 




20 



OK BJTfOK 



FREQUENCY- IN CYCLES PER SECOND 
Fig. 2. Overall 15-in./sec tape speed, record-reproduce frequency response. 



the input tubes. This is derived from a 
full-wave selenium rectifier. 

The output of the playback system 
consists of two independent 10-w ampli- 
fiers with nominal output impedance 
of 4 and 1 6 ohms. A 600-ohm balanced 
connection is also provided at a line 
level of +4 dbm for each channel. The 
system is both pre- and post-equalized 
in order to achieve a flat response at 
15 in./sec recording speed of from 50 
cycles to 15 kc 2 db (Fig. 2). Both 
the amplifier unit and the tape transport 
are provided with facilities which allow 
operation at 7-g- in./sec with a frequency 
response of from 50 cycles to 7.5 kc 
2 db. 

A signal-to-noise ratio in the order of 
50 db is achieved with this equipment. 
The residual crosstalk between channels 
is essentially due to low-frequency 
magnetic coupling below 100 cycles/sec. 
This crosstalk measures approximately 
35 db at 50 cycles and drops with fre- 
quency increase until it goes below the 
tape noise level at a little over 100 
cycles/sec. 

Calibration Means 

In order to assure accurate localizing 
based upon binaural amplitude com- 



parison, it is desirable that all possible 
electronic balancing between the two 
record-reproduce channels be carried 
out. To this end, a calibration button 
is provided which inserts a 60-cycle/sec 
signal simultaneously into the first 
stages of both amplifier inputs. The 
channel gain controls may then be 
individually adjusted to obtain equal 
VU meter readings. The balanced 
signals may then be recorded if the tape 
transport is turned on. When played 
back, the two 60-cycle signals may 
again be read on the VU meters and the 
playback gain controls may then be 
balanced for the optimum binaural 
effect. 

Commercial Applications 

The design of this equipment was 
aimed at satisfying certain specific 
commercial applications although it 
has a definite application to high- 
fidelity music recording-reproducing, 
where listening pleasure is desired to 
be as high as possible. The majority 
of commercial applications lie in the 
field of identification of intelligence or 
information where it is necessary to 
distinguish between each of many 



114 



August 1952 Journal of the SMPTE Vol. 59 




Fig. 3. Binaural recorder in field use by auto manufacturer testing for noise. 



sound sources which may be spread 
around a given area. 

Court recording is one very important 
and useful application of this equipment. 
With it, accurate records including 
differentiation between the various per- 
sons in a courtroom may be made. 
A study by Ray Hirst 6 of monaural 
court recording has shown that too 
often court records are at variance 
with what actually transpired because 
the court clerk was unable to follow 
testimony fast enough to accurately 
transcribe data as it was presented; or 
because the clerk heard something wrong; 
or because the clerk simply made a 
mistake. On one occasion, to our 
knowledge, it was necessary to reverse 
the written record due to a stenographic 
error. Application of this equipment 
to a Court of Justice would help to 
improve the carrying out of justice. 
We have carried out courtroom tests 
with very effective results and have 
some excellent demonstration tapes. 

Another application of this binaural 



technique is that used by police^and 
secret-service departments for secret 
recording of conversations. The stand- 
ard accepted methods of masking a 
voice's intelligibility are by the use of 
continuous tapping noise, by the run- 
ning of faucet water or by the turning 
up of a radio for background masking 
noise. A monaural system cannot dis- 
tinguish between the masking noise 
and the intelligence it is desired to 
detect. A binaural system localizes 
the attempt at masking and allows the 
listener to associate direction with the 
desired sound so that he may achieve 
intelligibility. 

Business, technical or military con- 
ference proceedings are a natural for 
this type of recording since the data 
may later be transcribed by a stenog- 
rapher with considerable freedom from 
error caused by simultaneous talking 
or masking. A stenographic transcrip- 
tion may be made of two people talking 
simultaneously since by mental localiza- 
tion the stenographer may concentrate 



Otto C. Bixler: Binaural Recorder 



115 



on the speakers one at a time and then 
play back the recorded material a 
second time to get the second speaker. 
In some recently conducted tests it was 
found that if two conversations are 
simultaneously recorded, a capable 
operator can produce an accurate 
transcription even when the desired 
conversation was recorded at a 13-db 
lower level than the unwanted dialogue. 

In radio and motion picture work the 
second recording channel may be used 
as a cue or control track for special 
effects or for recording commentary 
along with the primary intelligence. 

In the laboratory or for field-test 
work the binaural equipment may be 
used for recording either binaural or 
dual-track test data for later careful 
analysis. Figure 3 shows a binaural 
recorder in field use by a prominent 
automobile manufacturer. Note that 
this setup shows the predecessor to the 
dual-channel amplifier unit. 

The field of audio-visual education 
utilizes realism as a teaching aid. This 
portable binaural packaged system 
readily lends its "third-dimensional" 
sound reality to assist in critical analysis 
of band or choir practice, speech classes, 
dramatics, etc. 

Conclusion 

1 . No appreciable sacrifice in quality 
from that of a standard ^-in. tape re- 
cording system was necessary in these 
units. 

2. The resultant equipment as manu- 
factured is really of a portable nature 
and is housed in two carrying cases. 
The amplifier unit weighs but 37 Ib, 
while the tape transport has a weight 
of 29 Ib. 

3. From the foregoing data, it is 
apparent that the design objectives of 
producing a practical but low-cost 
commercial binaural record-reproduce 
magnetic tape equipment were accom- 
plished. 



References and Bibliography 

1. Stereophonic Sound-Film System, a sym- 
posium of seven papers presented May 
1941 at the Spring Meeting of the 
SMPE at Rochester, N.Y. Published 
as Bell Telephone System Monograph 
B-1327, 1941; and in Jour. SMPE, 37: 
331-426, Oct. 1941; consisting of: 
H. Fletcher, "General Theory"; 

E. G. Wente, R. Biddulph, L. A. Elmer 
and A. B. Anderson, "Mechanical 
and optical equipment for the stereo- 
phonic sound-film system"; 

J. G. Steinberg, "Pre- and post-equali- 
zation of compandor systems"; 

W. B. Snow and A. R. Soffel, "Electrical 
equipment for the stereophonic sound- 
film system"; 

E. G. Wente and R. Biddulph, "Light- 
valve for the stereophonic sound-film 
system" ; 

E. G. Wente and A. H. M{Uler, "In- 
ternally damped rollers"; 

L. A. Elmer, "A non-cinching film re- 
wind machine." 
Note: The first three of the above 

papers were published also in /. Acoust. 

Soc. Am., 13: 89-114, Oct. 1941. 

2. H. Fletcher, "Auditory patterns," Revs. 
Modern Phys., 12: 47-65, Jan. 1940. 

3. Wire Transmission of Symphonic Music 
and Its Reproduction in Auditory Per- 
spective, a symposium of six papers pre- 
sented at the Winter Convention of 
AIEE, Jan. 1934. Published as Bell 
Telephone System Monograph B-784, 
1934; in Elec. Eng., 53: 9-32, 216-218, 
Jan. 1934; and Bell System Tech. /., 
13: 239-310, Apr. 1934; consisting of: 
H. Fletcher, "Basic requirements"; 

J. C. Steinberg and W. B. Snow, 
"Physical factors"; 

E. G. Wente and A. L. Thuras, "Loud- 
speakers and microphones" ; 

E. O. Scriven, "Amplifiers"; 

H. A. Affel, R. W. Chesnut and R. H. 
Mills, "Transmission line"; 

E. H. Bedell and Iden Kerney, "Systei 
adaptation." 

4. Lorin D. Grignon, "Experiment 
stereophonic sound," Jour. SMPE, 
280-292, Mar. 1949. 

5. J. P. Maxfield, A. W. Golledge and 
T. Friebus, "Pick-up for sound moti( 
pictures (including stereophonic)," Jo 
SMPE, 30: 666-679, June 1938. 



116 



August 1952 Journal of the SMPTE Vol. 59 



6. Ray Hirst, unpublished work on court 
recording, (Eugene, Oregon) Official 
Court Reporter, 2nd Judicial District, 
State of Oregon. 

Discussion 

R. H. Ranger (Rangertone, Inc.) : Through 
the courtesy of the Magnecord Company, 
I have had the privilege of using one of 
these equipments and I want to say that 
it is certainly most intriguing to have the 
opportunity to do so. The particular 
reason they were anxious to have me try 
it was to see if we could record a syn- 
chronizing signal on this same tape and I 
can report to you people who are obviously 
very interested in synchronizing that it 
is quite feasible. We have recorded the 
longitudinal track in the center between 
the other two tracks, so that you can get 
synchronous operation using this binaural 
equipment. 

I might just add one little reaction that 
I have had with it and which I confirmed 
with Dr. Fletcher just yesterday in New 
York, and that is that not only is it in- 
teresting to get two speakers differentiated 
spatially by this process, but the actual 
quality of a single speaker, a single person 
singing, or a single instrument seems to be 
improved. As Dr. Fletcher said, "I'm 
too old to figure that out. We'll have to 
leave that to the younger people." 

Anon: Is there any provision in your 
equipment for playback on one channel 
while recording on the other? 

Mr. Bixler: No, there is not at the present 
time. 

Anon: I have asked that only because 
there are several applications for which 
I think that would be a very useful feature. 
One of them, for instance, is prescored 
accompaniment in music, while the person 
! practices his solo beside it. 

Mr. Bixler: I might say that there is a 
single multiple contact selector switch 
which is used to switch both channels 
simultaneously from record to playback, 
and that you could do what you suggest 
if you were to go into the circuit and build 
in two switches, in place of this single 
switch along with seme other minor 
modifications. 

C. H. Lankester (United Nations) : In 
view of the fact, as I understand it, that 



there is a longitudinal displacement be- 
tween the record heads, have you found it 
possible to standardize a positioning of 
the two heads perfectly accurately, that 
a binaural recording made on that recorder 
would play back on another without loss 
of the binaural effect? 

Mr. Bixler: I might say that the speed 
of the tape actually helps in this respect 
because it's relatively fast and each wave- 
length covers quite a bit of tape when 
you "lay" down the signal. On the 
other hand, heads are supported in fixed 
castings so that these same patterns are 
used in all our machines it's the stand- 
ard casting we've been using for years, 
so that insofar as our equipment is con- 
cerned, the location of the heads auto- 
matically falls in identically the same 
position in each and every machine. If 
there is some minor spacing difference 
the speed of the tape is sufficiently great 
so as to swamp that difference out. 

John G. Frayne (Westrex Corp.): I would 
like to ask Mr. Bixler if he found it im- 
possible to put the two separate heads 
in the same head structure because the 
crosstalk between them would then be 
undesirable. 

Mr. Bixler: Well, yes and no. I imagine 
if we had tried to put them right alongside 
of each other we would have had some 
crosstalk and I looked with interest at 
Charlie Davis' disclosure in a recent 
SMPTE Journal., but it was a matter of 
expediency in utilizing present equip- 
ment and space location on existing 
castings on which, as I mentioned, we 
simply replace the existing record and 
reproduce monitor heads in standard 
equipment. Thereby it turns out that 
the heads are spaced from about one-half 
to about three-quarters of an inch apart 
automatically. 

Dr. Frayne: What is the separation now 
between the two half-tracks between 
the two components, rather, approxi- 
mately? 

Mr. Bixler: I don't know. 

John Boyers (Magnecord, Inc.) : 50 thou- 
sandths of an inch. 

Mr. Bixler: Thank you, John. 

Dr. Frayne: I believe that with about 
50 thousandths separation you might work 
in the decoupler such as Davis discloses. 

Mr. Bixler: Yes, that is if we had heads 
that were suitable for that type of mounting. 



Otto C. Bixler: Binaural Recorder 



117 



Follow-Focus Device and Camera Blimp 
for 16mm Professional Camera 



By LEE R. RICHARDSON and WILLIAM N. GAISFORD 



A novel system of lens focusing, coupled with a synchronized parallax correc- 
tion cam and focusing viewfinder, is accomplished by the use of planetary 
gearing to the lenses which also permits fast shifting of lenses without dis- 
engaging any cams, gears or footage dials. A plastic camera blimp for the 
16mm professional camera and follow-focus mechanism is introduced which 
reduces the noise level to permit professional sound cinematography. 






A RODUCERS OF 16mm television and 
industrial films are frequently con- 
fronted with the problem of photo- 
graphing a live show, sporting event or 
other unrehearsed productions which 
cannot be repeated. In many instances 
when filming these shows, it is necessary 
to follow a moving subject which may 
move toward or away from the camera 
making it necessary to keep the subject 
in proper focus and suitably composed 
on the film. Further, a camera blimp 
is often required which will reduce the 
noise level of the camera to permit 
sound recordings under the most critical 
sound conditions. 

The Raphael G. Wolff Studios of 
Hollywood, producers, of television and 
commercial productions, were faced 
with problems similar to the above. 



Presented on April 25, 1952, at the Society's 
Convention at Chicago, 111., by Benjamin 
Berg for the authors, Lee R. Richardson 
and William N. Gaisford, Richardson 
Camera Co., 1065 N. Fairfax Ave., Holly- 
wood 46, Calif. 



After consultation with the Richardson 
Camera Co., they submitted specifica- 
tions for a follow-focus device and 
camera blimp for a Maurer 16-05 Pro- 
fessional Camera equipped with 15-mm 
//2.5, 25-mm //1 .4 and 40-mm //1. 4 
Eastman Cine Ektar lenses. 

The Wolff Studio's specifications called 
for the development and manufacture 
of a mechanism to permit follow- 
focusing of each lens of a multiple-lens 
turret through their focusing range 
(3 ft to infinity), provide a simple and 
efficient means of shifting to another 
lens of a different focal length at any 
time, maintain the same focus setting 
as the preceding lens without interfering 
with the functions of racking over the 
camera or threading the film in the 
camera and enable the operator to keep 
subjects constantly in sharp focus and 
suitably composed on the film as the 
distance between subject and camera 
position varies even though the subject 
may move away from or toward the 
camera in a direct line or at an angle. 



118 



August 1952 Journal of the SMPTE Vol. 59 



The requirements of the blimp were 
to contain the camera and follow-focus 
mechanism and be constructed of a 
sound deadening material, be light- 
weight, and reduce camera noise inter- 
ference to a level permitting the use of a 
microphone within 3 ft of the camera. 

The Maurer Camera was ideally 
suited to this project as it comes equipped 
with a focusing viewfinder with a 
parallax compensating mechanism. 

Design and Construction 

A planetary system of gearing was 
selected as it made possible the functions 
of keeping the entire gear driving mech- 
anism and viewfinder linkage per- 
manently engaged. The fact that all 
three lenses are caused to rotate simul- 
taneously in their mounts is not objec- 
tionable (Fig. 1). 

Each lens was set up in a dividing 
head and the amount of rotation from 
the 3 -ft mark to the infinity mark were 
obtained in order to determine the 
correct gear ratios for synchronizing the 
lens calibration with the focusing dial 
and control knob. 

The main drive gear consists of a ring 
gear having both internal and external 
gear teeth of 48 pitch with annular 
ball races ground on both faces of the 
gear and loaded with 480 -jVin. steel 
balls. Two retaining gear rings are 
grooved to match the ball races which 
hold it in place on the front of the camera 
case. The balls are slightly preloaded 
to allow the ring gear to rotate with 
minimum friction and no end play. 

Compound gears of proper ratio are 
driven by the internally cut teeth of the 
ring gear and are ball-bearing mounted 
on fixed stud shafts attached to the lens 
turret plate. These gears in turn mesh 
with the ring gears attached to the lens 
focusing barrel. 

A gear transfer case transmits motion 
from the control knob and dial assembly 
to the externally cut teeth on the ring 
gear and also to a master cam plate 
gear housed in the subbase of the 



camera. These two gears are syn- 
chronized with a ratio of one to one. 

The master cam plate has three scrolls 
(Fig. 2) each generated and cut to act 
upon a cam follower and linkage to the 
Maurer focusing viewfinder. The cam 
is spring loaded against the scroll to 
eliminate backlash. 

The viewfinder was modified to func- 
tion with a minimum of friction and 
backlash by removing the rack and 
pinion and replacing the dovetailed 
slides with ball rollers. As the Maurer 
viewfinder has two parallax compensat- 
ing cams, one for the wide-angle lens, 
15-mm, and the other for the 25-mm 
and 40-mm lenses, an adjustable link- 
age was provided for manually shifting 
the finder only for the wide-angle lens. 

The control knob and dial assembly 
is one detachable unit and can be 
mounted on either the left or right side 
of the camera. A splined coupling 
permits engaging the control unit to 
several reading angles. 

Operation 

A simplified sketch is shown (Fig. 3) 
which illustrates the basic principle 
involved in the operation. 

Control knob (a) drives gear (b) 
which in turn rotates internal ring gear 
(c) causing gears (d, e, f) to rotate, in 
turn causing gears (g, h, i) to revolve, 
By proper gear ratios, (g, h, i) rotate 
lens focusing barrels (j, k, 1); thereby, 
keeping all lenses synchronized in 
respect to their focusing range from 
infinity to their nearest focal point. 
When lock (n) is released from notch 
in turret plate, and control knob (a) is 
rotated in either direction, the entire 
lens-mount assembly attached to the 
mounting plate (m) will rotate until 
by-pin (n) drops into next indexing 
notch in plate (m). All lenses will 
remain in the same synchronized focus 
position as the lens mount assembly is 
shifted from one lens to another because 
the resistance of the lens-focusing barrels 
and the gearing will overcome the lighter 



Richardson and Gaisford: Focus Device and Blimp 



119 




Fig. 1. Planetary gearing system to lenses. 




120 



Fig. 2. Master cam plate and viewfinder linkage. 
August 1952 Journal of the SMPTE Vol. 59 




Fig. 3. Schematic drawing of basic principle of planetary gear system. 



friction of the mounting plate (m). In 
shifting from one lens to another, the 
focus dial (o) will rotate one complete 
revolution thereby returning to the same 
distance calibration as the preceding 
lens. 

Example: In the case of a three-lens 
turret assembly, as illustrated, the gear 
ratio between the control knob (a) and 
the internal ring gear (c) is 3 to 1 with 
three indexing notches on the lens 
turret plate, one to index each of the 
three lenses. Focus dial (o) will rotate 
one complete revolution in shifting 
lens-mount assembly to next lens. This 
will allow the use of only one focus dial 
for all three lenses. 

The follow-focus operation incor- 
porates, in addition to the foregoing 
system of lens focusing, a method of 
actuating the focusing viewfinder so 
that the optical elements of the finder 



sharply focuses the image on its viewing 
glass in synchronization with the lens 
focusing of the image on the film. 

A stop pin within each lens mount 
prevents the lenses from rotating beyond 
their infinity position. This in turn 
prevents the control knob from being 
further rotated due to the lens turret 
plate assembly being locked by the 
turret locking pin. When a release 
button is pressed and the control knob 
turned, the entire lens turret assembly 
rotates until the next lens is in place, 
indexed and locked by the turret locking 
pin. Synchronized with this function is 
the cam follower which rides out of its 
cam scroll into an inclined circular 
groove and drops down into the next 
cam scroll and is synchronized to the 
next lens that comes into place. 

The linkage from the cam follower 
to the focusing viewfinder is so con- 
structed to permit racking over the 
camera for lining up a scene and also 



Richardson and Gaisford: Focus Device and Blimp 



121 




Fig. 4. Three-quarter front view, showing window over camera lens. 



for opening the camera door to rethiead 
the film. The viewfinding actuating 
cam scrolls were generated to their 
respective lens-focusing distances at the 
full lens opening. The depth of the 
field of the lenses allows for normal 
human error in follow-focusing on a 
moving subject or when the camera is 
mounted on a moving platform in rela- 
tion to a fixed subject. 

Camera Blimp Design and Construction 

The component sections of the blimp 
(Figs. 4 and 5) were designed to take 
advantage of the simplified method of 
fabrication which is possible with 
Royalite Plastic, a product of the U.S. 
Rubber Co. 

The base and cover sections are 
reinforced with an aluminum frame 
giving additional strength and support 
for the cover hinge. The interior of 
the blimp is further soundproofed with 
Royalite expanded plastic and finished 
off with a corduroy covering. A rubber 
grommet, around the edges of the lower 
part of the blimp, acts as a seal when 
the cover is closed. The camera mount- 



ing base is a steel plate cemented 
the inner base of the blimp with 
|-in. thick pad of neoprene spon 
rubber between. Guide rails are 
tached to the base plate to register t 
camera when installing in the blim 
An aluminum alloy plate is rubbe 
bonded to the bottom of the blimp 
providing a firm support for the entire 
unit when mounted on a tripod, camera 
dolly or platform. 

Other main features of the blimp are: 
(1) an optical glass window which 
hinged permitting access to the lenses 
for setting / stops; (2) portholes for 
observing /-stop markings when blimp 
cover is closed and to check on magazine 
take-up wheels; (3) external control 
for turret release button; (4) pilot light 
to illuminate the interior of the blimp 
when making lens adjustments, thread- 
ing, etc.; (5) jeweled indicator lights 
which show when camera motor is 
running and pilot light is on; and (6) 
windows in the rear of blimp for looking 
through viewfinder, checking shutter 
openings and footage counter. 



^a 

= 



122 



August 1952 Journal of the SMPTE Vol. 59 




Fig. 5. Side view, showing control knob and dial assembly. 



Comments 

The Richardson Camera Co., when 
designing the lens-focusing system, were 
aware of the discrepancies between the 
three lenses. The problem, however, 
was not to construct an absolutely ac- 
curate focusing system as would be 
required on precision optical printers 
but to provide an efficient, simple and 
quick method of follow-focusing for the 
cinematographer on action shots. 



In focusing a lens on a variable mov- 
ing subject, it is necessary for the camera 
man or his assistant to estimate or 
determine by some visible means the 
distance between the camera and sub- 
ject. He must then transfer this in- 
formation to the lens-focusing control 
knob or footage dial all of which in- 
volves a human function with limited 
accuracy. The depth of focus of the 
lens in use is intended to permit a 



Richardson and Gaisford: Focus Device and Blimp 



123 



certain amount of error in the judgment 
of the operator. 

The designers increased the accuracy 
of the mechanism by calibrating the 
footage dial to the longest focal length 
lens used, 40-mm at //1. 4 stop. Ob- 
viously, where critical focusing is re- 
quired, the camera is racked over and 
the subject aligned and focused on a 
ground glass. This is the most accurate 
means of focusing and does not depend 
on footage calibrations engraved on the 
lens. This means of focusing cannot 
be used when the subject or camera is 
in motion. 

Conclusions 

The follow-focus device was found 
to be exceedingly efficient as to the 
accuracy of the mechanism and as to 
simplicity and time-saving in operation. 
The knowledge that the lens parallax 
and distance calibrations are at all times 
synchronized gives, to the operator, 
assurance that a sharp focused and 
composed image is properly recorded 
on the film. 



The lightweight plastic blimp was 
tested on i sound stage under normal 
operating conditions and found to be 
equal in performance to other blimped 
professional motion picture cameras. 
In most cases, the front glass was left 
off and still the camera noise was below 
the ambient sound noise of the stage 
making it possible to record dialogue 
with the microphone within 3 ft of the 
camera. 

Acknowledgments 

The authors wish to acknowledge the 
sponsorship of this project by the 
Raphael G. Wolff Studios, to Mr. 
Wolff personally and his camera tech- 
nicians Art Treutlaar, Gail Papineau 
and Henry J. Ludwin, all of whom 
outlined the essential requirements in- 
corporated in this design. Charles L. 
Bluske, industrial designer, styled the 
camera blimp. John Roy of the U.S. 
Rubber Company gave technical advice 
on fabricating Royalite Plastic material. 
The Glen Glenn Sound Co. gave its 
sound stage facilities for testing the 
performance of the equipment. 



124 



August 1952 Journal of the SMPTE Vol. 59 






Instantaneous Theater Projection 
Television System 

By VICTOR TRAD and RIGARDO MUNIZ 



A new, inexpensive, instantaneous dual theater projection television system 
of the Schmidt type is described. A simple control box providing almost 
instantaneous change-over, in the event of breakdown, and mechanical 
arrangements facilitating ease of installation and maintenance are discussed. 



STUDY of the needs of the motion 
picture theater owner and operator 
made over a period of many years, in 
connection with the development of this 
and earlier projection television units, 
has revealed the need for a thoroughly 
satisfactory and reliable theater pro- 
jection television unit which will, at 
the same time, be substantially lower in 
cost than those others currently available, 
and which will be amenable to relatively 
simple installation techniques, and which 
can be supplied and kept in adjustment 
easily by the motion picture projection 
machine operator. This paper pre- 
sents some of the technical and opera- 
tional features of the present Trad 
theater television unit. 

It will be seen that, in this typical 
installation (Fig. 1), the Trad dual 
unit rests upon a simple support bracket 



Presented on April 21, 1952, at the Society's 
Convention at Chicago, 111., by Frank H. 
Riffle for the authors, Victor Trad and 
Ricardo Muniz, Trad Television Corp., 
1001 First Ave., Asbury Park, NJ. 



which, in turn, has been attached to the 
main balcony support of the theater. 

This places the unit in the proper 
operating position with respect to the 
theater screen, and also provides maxi- 
mum accessibility from the balcony of 
all adjustments and chassis for routine 
operation and maintenance. 

Figure 2 shows how the two chassis, 
the low-voltage power supply with 
video amplifier and the high-voltage 
sweep chassis, are mounted with rela- 
tion to the projection optical system, 
and also how accessible the units can 
be from the balcony without the use of 
ladders or scaffolding. 

The various electronic adjustments 
are located in the rear of the high- 
voltage sweep chassis and, once made, 
need be checked only at infrequent 
intervals, but which are conveniently 
accessible from the balcony since they 
are on the side of the chassis nearest 
the balcony. It is important to note 
that this is the only place in the entire 
installation where any high voltage 
exists. It is not necessary to have 
elaborate high-voltage transmission sys- 



August 1952 Journal of the SMPTE Vol. 59 



125 






Fig. 1. A theater installation, showing the dual unit mounting 



terns nor protective devices with the 
Trad theater television unit. 

The remote-control unit (Fig. 3) is 
mounted in the motion picture pro- 
jection booth near one of the port holes. 
This remote-control unit provides for 
the adjustment of contrast, vertical and 
horizontal hold, and also for the switch- 
ing from one of the dual units to the 
other, in the event that any trouble 
develops in the one in operation. It is 
here that the operator stations himself 
and it is these^ controls alone which he 
will find it necessary to manipulate 
during the normal operation of the 
equipment. 

Signals are provided by a monitor, 
Fig. 4, containing a television receiver 
and providing video amplification for 
any remote programs from either 
microwave link or the coaxial cable. 



It also provides a third service in that 
the television receiver which it contains, 
when connected to a suitable antenna, 
can provide off-the-air signals from local 
television broadcasters, should these 
be required. 

Getting back to the main unit. Figs. 
5A and 5B show some of the unique 
features which have resulted from the 
long practical experience with this type 
of device. The patented Trad theater 
projection television unit was designed 
not only from the standpoint of opera- 
tional simplicity but also to project the 
greatest possible amount of light from 
the projection tube to the screen. 

As can be seen, the obstacles to the 
reflected rays of light have been mini- 
mized. It is interesting to note that, 
with a mirror diameter of 14 in. and 
a focal length of 6.6 in., the effective 



126 



August 1952 Journal of the SMPTE Vol.59 




Fig. 2. Close-up of one side of the unit, with protective 
hood open. 




Fig. 3. Remote-control unit. Fig. 4. The monitor. 

Trad and Muniz: Theater Television System 127 



aperture of the Schmidt optical system 
used is//0.85. 

- _ focal length 
effective diameter 



6.6 in. 

7.77 



0.85 



Light-meter readings taken at the 
surface of the corrector plate are 160 
ft-c. The optical barrel provides for 
adjustments of vertical and horizontal 
centering, conveniently accessible from 
the balcony by swiveling and tilting 
the barrel, and also for overall top-to- 
bottom optical focus. The convenience 
of these adjustments can be readily 
appreciated by any user who has at- 
tempted to make these adjustments on 
other types of television projection 
barrels. 

It will be noted in Fig. 5A that the 
vertical and horizontal focus adjust- 
ments are accomplished by moving the 
"dish," which is the curved-front sur- 
faced reflector in the optical barrel, 
vertically or horizontally by screw- 
operated mechanisms controlled by the 
two knobs shown for each direction. 
Similarly, as in Fig. 5B, the optical 
focus control has been brought forward 
by mechanical means so that a simple 
knob within easy reach of the balcony 
is all that need be controlled. In 
installations having the optical system 
higher than the center of the theater 
screen it becomes necessary, of course, 
to tilt the barrels downward in order 
to throw the picture within the dimen- 
sions of the screen. In doing this it is 
found that, if the optical focusing 
adjustment is carefully set for the center 
of the screen, the top and the bottom 
of the picture are somewhat out of focus. 

By adjusting the vertical and hori- 
zontal focus adjustment knobs in the 
rear of the barrel, the picture can be 
brought into good overall focus without 
having to tilt the screen. A high degree 
of "practical" engineering has gone 
into the Trad barrel as a result of many 



years of acrobatic hanging by one foot 
from theater roofs, perching on the top 
of fire-engine ladders or chinning one- 
self on a trapeze while using the teeth 
for adjustment purposes. So, here now 
is a barrel which doesn't require an 
acrobat, or any unusual courage or 
skill to operate. It may be noted in 
passing that there is symmetry about 
the center of the dual unit, with the 
left-hand and right-hand units being 
mirror images. Each of them inde- 
pendently provides all of the necessary 
adjustments in equally accessible form. 

There are three unique technical 
features worthy of attention: (1) the 
high-voltage multiplier supply; (2) the 
automatic brightness control; and (3) 
the video amplifier response characteris- 
tics. Taking these in order: 

The high-voltage tripler operates on a 
very interesting principle. Figure 6 is 
a simplified schematic showing the 
operation of the voltage multipliers. 
It will be noted that the 6BG6 tube 
shown in the diagram is one of the 
horizontal deflection amplifiers which 
supplies the proper waveform of current 
to the horizontal deflection coils, which 
cause the electron beam to scan the face 
of the cathode-ray tube horizontally 
during operation. At the end of each 
horizontal line, the 6BG6 plate current 
is "cut off" after the incoming hori- 
zontal sweep signal drops to zero. A 
positive pulse of voltage appears at 
point A as a result of the collapsing 
field of the horizontal deflection coil 
(this is a kickback or flyback voltage). 
These positive pulses are first rectified 
by VI which is a diode vacuum tube, 
and the capacitor Cl is found to be 
charged to a value very near the peak 
value of the original pulse. Since the 
cathode of VI is connected to the plate 
of V2 through Rl , then C2 will charge 
up to the same voltage as Cl. The 
charge on C2 is thus added to the 
oncoming pulse and tube V2 rectifies 
the sum of these voltages, thus charging 
capacitor C3 to double the original pulse 



128 



August 1952 Journal of the SMPTE Vol. 59 




Figure 5A. Figure 5B. 

Views of the optical barrel. 



VI ftl V2 < R2 I 1V3 




Fig. 6. Simplified diagram of the high-voltage tripler. 




Fig. 7. Simplified diagram showing Rl and R2 replaced by V4 and V5. 

Trad and Muniz: Theater Television System 129 



voltage. The charge on C4 is added 
to the already duplicated incoming 
pulse voltage and V3 rectifies this po- 
tential to produce a charge on capacitor 
C5 of three times the incoming pulse 
voltage. In the case of this unit, the 
original pulse voltage is somewhat over 
10,000 v so that the output of the volt- 
age multiplier system is approximately 
33,000 v. 

The type of voltage tripler which was 
just described is conventional and is used 
on some other types of television pro- 
jection devices; however, practical ex- 
perience has shown that Rl and R2 
have such high voltage gradients that 
it is next to impossible to obtain re- 
sistors which will have long life and 
which will retain resistance stability 
for a reasonable period. Therefore, 
in the interests of maximum reliability, 
these resistors have been replaced in 
the Trad unit by two additional high- 
voltage diode rectifier tubes V4 and V5, 
as shown in Fig. 7, functioning as 
thermionic resistors and having longer 
life and greater stability. This was 
possible because the high voltage across 
the resistors was direct current; therefore, 
the vacuum tube could be connected 
in such a manner that it would present 
a high impedance to voltages of that 
polarity while permitting currents in 
the reverse direction to flow with rela- 
tive ease. Thus the vacuum tube 
provides a higher inverse resistance than 
would have been practical with re- 
sistors and still have the advantage of a 
low impedance in the reverse direction. 

Figure 8 shows this circuitry embodied 
in a completely enclosed plastic housing 
which provides large margins of safety 
with respect to arc-over or strike-over 
of high voltage between the circuit 
elements and/or ground. The simple 
and clean design which has been 
achieved can readily be seen in this 
high-voltage unit. It is interesting to 
note also that the five-tube tripler unit 
can be readily removed from the balance 
of its circuits for routine maintenance, 



and that this construction also pro- 
vides the maximum ease of replacement 
in the event of any form of failure in the 
unit. 

In Fig. 9, the capacitors Cl, C2, 
C3, C4 and C5 can readily be seen. 
It should be noted that there are no 
wires or other protuberances in the 
high-voltage compartment which would 
induce breakdowns. 

Figure 10 shows the actual circuitry 
in the high-voltage and sweep chassis. 
The circuit diagram shown herewith is 
fairly conventional, but may be worthy 
of a few words. The composite video 
signal has had the synchronizing in- 
formation stripped from it in the asso- 
ciated low-voltage power supply unit, 
shown in Fig. 11. This synchronizing 
information is fed into the unit shown 
and separated into both horizontal 
and vertical synchronizing pulses by the 
6SN7 vacuum tube. A blocking type 
of oscillator is used for the vertical 
deflection, whereas a synchro-lock type 
of horizontal oscillator circuit for maxi- 
mum synchronizing stability is used for 
the line frequency. The five-tube trip- 
ler, which was explained above, is seen 
in this diagram, together with its asso- 
ciated circuitry. 

Figure 11 is the schematic circuit 
diagram of the low-voltage power supply 
and video chassis. It will be noted, a 
two-stage video amplifier with series 
and shunt peaking is provided, and that 
a d-c restorer of conventional design 
as well as a synchronizing stripper are 
incorporated on this chassis. The un- 
conventional part of this unit is given on 
the right-hand side of the d-c restorer 
tube which, with its associated circuitry 
shown herewith, rectifies the video 
signal which appears across the plate 
load resistor of the second video ampli- 
fier stage and supplies this potential to 
the accelerator grid of the picture tube. 
This portion of the d-c restorer and its 
associated circuitry is an automatic 
brightness control. 



130 



August 1952 Journal of the SMPTE Vol. 59 





Fig. 8. The tripler assembly, top. 




Fig. 9. The tripler assembly, bottom. 
Trad and Muniz: Theater Television System 



131 



JF I Al 




Fig. 10. Circuitry in the high- 



The automatic brightness control 
circuit, Fig. 12, is a means of auto- 
matically adjusting brightness on a 
cathode-ray tube, utilizing the varying 
plate voltage of the video output tube 
to adjust automatically the accelerator 
voltage on the accelerator grid AG of 
the cathode-ray tube CRT. 



This automatic adjustment not only 
maintains the greatest amount of high- 
light brilliance at any amount of video 
signal input, but also prevents the 
cathode-ray tube from blooming, that is, 
it prevents abnormal enlargement of 
picture or raster. This in effect is 
accomplished by varying the accelerator 



132 



August 1952 Journal of the SMPTE Vol. 59 




voltage and sweep chassis. 



voltage upward when the video signal 
is increased and downward when video 
signal is decreased. 

If the automatic brightness circuit is 
not used, and a high fixed voltage is ap- 
plied at AG at greatest video signal 
input, the highlight brightness of the 
image is high; but upon decreasing the 



video signal, the brightness of the raster 
remains the same and the high voltage 
at HV decreases gradually until the 
signal is removed. Then the raster 
"blooms" and becomes "milky," and 
the high voltage at HV shoots up to its 
maximum, possibly causing arc-over 
in the system. 



Trad and Muniz: Theater Television System 



133 




*i pf 






Fig. 11. Circuit diagram of the low- 



If, on the other hand, a low fixed 
voltage is applied at AG at the greatest 
signal input, the highlight brightness is 
not as high as when the above automatic 
circuit is used, but the voltage at HV 
is at a higher point than above. Then, 
upon decreasing the video signal, the 
high voltage decreases and the raster 
brightness remains the same even 
after the signal is removed. 



From the two conditions described, 
it is found that, at the high signal input, 
the picture should be brightest; there- 
fore, the volts at AG should be at a 
maximum. This keeps voltage at HV 
at a fixed high-voltage point for greatest 
possible highlight brightness. As the 
signal is decreased, the voltage at AG 
should be decreased, so that the voltage 
at HV remains very close to its high- 



134 



August 1952 Journal of the SMPTE Vol. 59 



MALE BANANA PLUS 
TO HIGH-VOLT. CHASSIS 




voltage power supply and video chassis. 



voltage point, giving the brightest 
possible picture at this setting. Upon 
the removal of the signal, the voltage 
at AG should be brought to its lowest 
point for proper operation to prevent 
blooming and the voltage at HV con- 
tinues to decrease normally prevent- 
ing the failures and breakdowns as 
explained previously. Also, it is readily 
seen that changing from station to station 



in this system will cause a decrease of 
voltage at HV making a very effective 
safeguard against breakdown. 

Potentiometer R, Fig. 12, is a manual 
adjustment of this proper minimum and 
is used to compensate for variables in 
different units which may cause this 
minimum voltage to be too high, thus 
causing blooming and the shooting up 
of the voltage at HV. 



Trad and Muniz: Theater Television System 



135 




Fig. 12. Automatic brightness control circuit. 



The use of a manual brightness control 
would satisfy the necessary conditions 
for optimum picture performance, but 
the addition of another control for the 
operator to set tends to make the 
operation of the unit a bit more com- 
plicated. The ideal condition is to 
eliminate the use of manually operated 
controls and obtain optimum per- 
formance settings automatically. The 
"Trad" automatic brightness control 
circuit described above accomplishes 
this with a high degree of efficiency. 
This system, in addition to being an 
automatic brightness control, is also an 
automatic high-voltage regulator keep- 
ing the voltage safe at the varying input 
signal levels. 

The graphs in Fig. 13 reveal the 
action of the automatic brightness 
control with varying video inputs. Also, 
shown in Fig. 14 is the interrelationship 
of average beam current resulting from 
the effect of the automatic brightness 
control as the video signal is varied. 
These graphs were made using a flying- 
spot scanner picture generator, and 
varying the output signal voltage, going 
from no picture, through all the inter- 
mediate stages, to a condition of maxi- 
mum contrast. 

One of the important design features 
of the Trad theater projection television 
unit is the picture quality, which is the 
result of critical peaking of the video 



amplifier circuits to produce a picture 
of maximum crispness without ringing 
or smearing. It will be noted from the 
curve in Fig. 1 5 that the usable response 
has been extended to approximately 7 
me, being more than adequate for clear 
and crisp picture reproduction from 
either closed-circuit or off-the-air opera- 
tion. 

No less important to the theater 
owner and operator is the low cost and 
relative ease of installation of this 
equipment. Surveys of many theaters 
were made before design decisions were 
arrived at, with the result that much 
less special work need be done in the 
theater during the installation of this 
equipment than many others currently 
offered. 

It will be noted, in referring to Fig. 1, 
that associated dual video amplifier, 
sweep, and high- and low-voltage supply 
chassis are installed in a convenient- 
sized housing which is supported at the 
fore part of the balcony on a single 
fabricated bracket which is supplied 
by Trad. This bracket is mounted by 
means of bolts through the structural 
support in the balcony. When mounted 
in this position, it is out of harm's way 
and yet is readily accessible for routine 
maintenance and adjustment. 

Figure 16 shows the simplicity of the 
complete electrical wiring of the system, 



136 



August 1952 Journal of the SMPTE VoL 59 



ft 20 40 60 80 10 


zzo 

210 
200 
190 
180 


220 


AUTOMATIC 
MANUAL B 


BRIGHTNESS 
IGHTNESS ( 


OPERATION 
PERATION 










ACCELERATOR GRID VOLTAGE^ 

s s s 1 8 i 






GOOD CONTl 


AST RANGE 


/ 


X 

M 


^H 






r 


/ 






/ / 


X 






X 


"/' 


)TE: CIRCLE 
ITICAL ADJU 
)OD OVERAL 
ANUAL OPE 


POINTS RE 
STMENT TO 
. BRIGHTNES 
ATION. 


UIRED 
MAINTAIN 
5 ON 


170 


/ y 










160 


20 '0 60 80 00 



COMPOSITE VIDEO VOLTAGE R TO P. 



Fig. 13. Accelerator grid voltage vs. composite video voltage, peak to peak. 



20 40 61 


D 80 1C 



\A 

1.2 
I.C 
.8 

,-s 


1.4 
1.2 

i 

E 


J 

[1.0 

I 

E 
t 
J 

D 


\ AUTOM 
\\ MANUA 

\\ 


VTIC BRIGH1 

L BRIGHTNE 


NESS OPER) 
3S OPERATK 














\ 


A 




- 






X^ 

X 


N . 1 

"-*-'' 



> .0 * 


^ 

T^ 


.6 


NOTE: CIRC 

MAINTAIN C 
OPERATION 


.ED POINTS F 
OOD OVERAL 


GOOD CON 1 

EQUIRED CR 
L BRIGHTNE 


RAST RANG 
IT1CAL ADJU 
5S ON MANU 


STMENT TO 
U. 


D 20 40 60 80 l( 



COMPOSITE VIDEO VOLTAGE R TO P. 
f. 14. Average anode beam current vs. composite video voltage, peak to peak. 

Trad and Muniz: Theater Television System 137 



ion 


IOOKC 400KC IMC ! 


3 4 56789 IOMC 
























""" 


~^^ 


Ss^ 


S 


^** 


-^ 











































70 * 




















" 70 w 


so 






VIDEO AMPLIFIER , xr 
UNDER TEST IOOOUUF SC 


ULOSC 


1PF 








- so , 








T T . 


1 * 
I 

1 : 


WOA 4- |OK iwOO^F L 


q 






















a 









I 1 * 


j i 4 4 


4 






























, 


- 20 


















S 


\ 


IOOKC 400 KC IMC 








8 


IOMC 



Fig. 15. Video amplifier relative amplitude response with varying input frequency 

and constant input voltage. 



Fig. 16. Complete elec- 



BOOTH WIRING 

UTILITY BOXES MMINO MONITOR. 




138 



August 1952 Journal of the SMPTE Vol. 59 



necessitating no unusual or complicated 
wiring. 

While it is expected that development 
work will continue, the unit described 
is a frozen design and is in production. 
In conclusion, we have presented here- 
with the present stage of commercial 
availability of a simple, low-cost, instan- 
taneous theater television projection 
system. 

Discussion 

Robert E. Lewis (Armour Research Founda- 
tion) : How many lumens do you get out 
of the system? 

Frank H. Riffle (Motiograph, Inc.) : (Mr. 
Riffle read the paper.) The only actual 
measurement that we have made is at the 
corrector plate and it is about 160 foot- 
candles. 



Chauncey L. Greene (RKO Orpheum Theater, 
Minneapolis): Perhaps I am again trying 
to take in too much territory here, but I 
would like to see if we can't translate those 
figures somehow into a screen brightness. 
Did I understand you that 160 foot- 
candles of brightness, so to speak, of the 
face of the tube.. .? 

Mr. Riffle: No, that was at the correc- 
tor plate. 

Mr. Greene: Now, is there any way of 
arriving at an approximate ratio between 
that and the screen brightness for any 
given picture size, that is, could we, for in- 
stance, divide that area into the screen area 
and apply a factor of loss? 

Mr. Riffle: Yes and in calculating 
this, we find approximately 0.4 foot-candles 
of light at the screen, which may appear to 
be comparatively small; but the brightness 
of the picture observed is entirely satis- 
factory. 



trical wiring diagram. 

BOOTH WIRING 

CONTROL BOX TO BE LOCATED NEAR POR* HOLE 
FOR EASY MANIPULATION OF CONTROLS BJ 
OBSERVATION. 



NOTE 

(21 5-PRONO SOCKETS a PLATE 
SUPPLIED BY TRAD. 



PROJECTOR WIRING 



A.C. TO PROJECTOR "t 




Trad and Muniz: Theater Television System 



139 



Theater Television Progress 



By NATHAN L. HALPERN 



This is a report on theater television developments in terms of the industry, 
programs, program distribution and the public interest in this new medium. 



I 



N THE DEVELOPMENT of theater tele- 
vision, as in all modern communications 
media, the engineers have been the 
pioneers. The records show that as long 
ago as 1929, technical experiments in 
large-screen television were being con- 
ducted. Many engineers who have been 
engaged in pioneering this new field, 
will be interested in hearing of the prog- 
ress that has been made along trails they 
blazed. 

There are four areas covered in this 
report: (1) the industrial development of 
theater television; (2) programs for 
theater television; (3) the public's re- 
action to these programs; and (4) the 
distribution of programs to theaters. 
Since future engineering developments 
in this new medium are directly related 
to the practical economics of theater tele- 
vision, these areas are all important. 

Today there are over 75 theaters in 37 
cities from coast to coast with large- 
screen television equipment. This is in 
comparison to a single television-equipped 
theater three short years ago. In 
the past year alone, theater television has 
increased its seating capacity 600%; the 
number of cities with installations has 
risen 300%. Notwithstanding these 



Presented on April 21, 1952, at the Society's 
Convention at Chicago, 111., by Nathan L. 
Hal pern, Theatre Network Television, Inc., 
515 Madison Ave., New York 22, N.Y. 



impressive figures, theater television is 
only beginning to grow. There are 20,000 
theaters to go. 

Theater television installations will be 
made eventually in all motion picture 
theaters in the country. Although it is 
off to a fast start, theater television has a 
long way to go before it can fully realize 
its great potentials. The harnessing of 
this form of television by the motion 
picture industry will offer the public a 
new and different service. Theater tele- 
vision will become a valuable national 
resource dedicated to the entertainment 
and education of the public. 

Despite its early stage of growth, there 
have already been over 300 individual 
theater presentations of large-screen 
television programs. While most of 
these have been news and sports events, 
there have been a few special entertain- 
ment presentations, as well as special 
government and industry uses of theater 
television's closed circuits. With few 
exceptions, the early presentations were 
experiments, conducted to test public 
reaction to, and the operation of, theater 
television. They clearly demonstrated 
that this new medium satisfied and pleased 
its audiences. It has been, in fact, the 
public's acceptance that has caused the 
further development of theater television. 

Theater television has already proved 
that theater television programs can be 



140 



August 1952 Journal of the SMPTE Vol.59 



successful. The conditions necessary for 
successful special event presentations 
have been emerging in the past year. 
Exclusivity, proper promotion and some 
regularity are all desirable, if not neces- 
sary. Matinee sports presentations, 
which bring new sports audiences into 
theaters at unprecedented times, require 
all three of these conditions to be favor- 
able. 

The most publicized theater television 
programs to date were the series of prize 
fights presented last summer. This series 
of six fights, presented by Theatre Net- 
work Television (TNT), was offered to a 
public that was unacquainted with the 
medium, and for this reason the series 
was presented under adverse circum- 
stances. The boxoffice results were 
nothing short of startling. The overall 
average attendance for all theaters on 
all six TNT fights was 87% of capacity, 
despite the fact that two of the fights 
were not top attractions. 

This boxoffice average is only a partial 
indication of the great public interest in 
these theater television programs. On 
several of the fights, the numbers of 
people turned away from boxoffices for 
lack of seats were much larger than the 
number of people packed into the theaters. 
These turn-away crowds were only part 
of the larger population that would 
have attended, but for theater television's 
limited capacity to accommodate the 
public last summer. 

Of importance, too, was the attraction 
of part of the "lost audience" non- 
movie-goers to the motion picture 
houses. Theater television proponents 
had, from the outset, maintained that 
this new medium would attract new 
audiences. New audiences added to 
normal film audiences will expand theater 
attendance in the years ahead. 

It goes without saying that every 
major medium must pass through an 
investment period at the start, with op- 
erating losses until it has grown suffi- 
ciently. The pioneers in home television 
broadcasting made large-scale invest- 



ments and sustained high losses for years 
of operation losses that ran into 
millions of dollars for single stations 
before they were in the black. The 
significant thing about theater television 
is that it has experienced profits on some 
events from the outset. As compared 
with television broadcasting, theater 
television has required relatively small 
investments and its operating losses have 
been comparatively small. But before 
examining the credit side of the ledger, 
let's take a look at the debits. 

The losses incurred in early theater 
television have not been due to a lack of 
appeal in its programs or in the medium 
itself. These relatively small losses were 
attributable to three factors: (1) the few 
theaters sustaining the costs of big-time 
attractions; (2) the pricing policies 
followed by theatermen; and (3) the 
absence of a regular, year-round flow of 
programs and promotion. 

Last summer, the TNT series of prize 
fights was carried by an average of only 
12 theaters. In spite of the very small 
number of theaters which shared rela- 
tively high unit costs, it was remarkable 
how close to break-even these theaters 
came on most programs. Profits were 
made on individual fights. Naturally, a 
larger number of theater installations 
will reduce individual theater costs and 
turn losses into profits. And the profits 
will increase as the number of theater 
television exhibitors grows. 

A prime factor in the difference be- 
tween profit and loss on theater television 
events was the initial low admission price 
policy of exhibitors. At the beginning of 
the summer fight series, exhibitors were 
literally giving their products away to 
see whether people liked them. Some 
exhibitors seemed to treat theater tele- 
vision as a fight film, to be marketed as a 
bonus to the feature movie. The cost of 
theater television presentations added to 
film exhibition meant exhibitors would 
incur losses if regular movie admissions 
were charged. Many chose this course 
at the start, not realizing that the real 



Nathan L. Halpern: Theater Television Progress 



141 



boxoffice pull was theater television, not 
the movie attraction on such bills. 
Theaters charged as little as 54^ net 
admission for the first several theater 
televised fights. There was no trouble 
selling out on nights when film business 
was ordinarily in the doldrums. 

As theatermen saw the public demand 
and satisfaction, they began to adjust 
admission prices upward. Moreover, 
exhibitors began to realize that a theater 
television event was unique entirely 
different from a film which is shown con- 
secutively, or even a live stage show that 
is repeated throughout its run. A unique, 
televised event - - valuable for the 
moment requires special handling and 
pricing. 

By the time of the Robinson-Turpin 
bout, theaters had adjusted their admis- 
sion prices to an average well over $2.00. 
Every theater carrying the fight sold out, 
evidencing the public's enthusiastic ac- 
ceptance of this new entertainment 
medium. The average theater television 
gross was $5,000 per theater, with seating 
capacities ranging from 1,100 to 4,000 
seats. It became apparent that higher 
prices for earlier theater television events 
might have resulted in profits then, too. 
Moreover, concession sales in theaters 
boomed, increasing as much as 400% 
above average. 

I would like to give you an idea of 
theater economics on a successful theater 
television event at this early period. 
Perhaps the best way to do this is by tak- 
ing a specific example: the economics of 
Theatre X, an actual theater, for one of 
last summer's TNT fights. Theatre X 
has 3,300 seats. With a $2.40 gross ad- 
mission price, and a sellout with 473 
standees crammed in, the net receipts, 
after taxes, were $7,500. Total television 
costs to the theater (relatively high be- 
cause of so few theater installations) 
were $4,000, leaving an operating tele- 
vision profit of $3,500. The deduction of 
normal house expenses and film distrib- 
utor costs still left this exhibitor with a 
whopping profit for a single theater tele- 



vision show. His only regret was that he 
had to turn away thousands of disap- 
pointed people, for lack of room. 

The economics of theater television 
last summer on such individual events 
clearly pointed up future prospects. If 
this kind of operating profit could be 
produced at the outset, with only a hand- 
ful of theaters, the outlook for programs 
carried by hundreds and then a thousand 
or more theaters is fabulous. 

The third factor affecting early theater 
television the absence of a regular, 
year-round flow of programs is due 
in part to the newness of the medium. 
The development of entertainment at- 
tractions, to go along with outstanding 
sports events, has preoccupied those of 
us in theater television these past several 
months. The entertainment desirable for 
theater television must, of course, be 
superior. Even now, theater television 
is growing closer to the number of outlets 
necessary to support regularly high-cost 
presentations and talent. 

In the developmental work put into 
entertainment for theater television re- 
cently, talent and craft unions were faced, 
for the first time, with making decisions 
on theater television. Most of these 
unions have recognized the importance 
of this new field and its gainful employ- 
ment and compensation potentials for 
their memberships, as well as its public 
service aspects. Consequently, their at- 
titudes are becoming progressively more 
cooperative. Meanwhile, however, time 
has been consumed in establishing a basis 
for entertainment in theater television. 

It is encouraging to report that there 
is a wealth of superior talent and enter- 
tainment eagerly awaiting the develop- 
ment of theater television. There is no 
lack of great entertainment, superior to 
home television and different from mo vies, 
for theater television programs. Once 
the ground rules have been worked out, 
TNT will launch a schedule of these great 
programs. 

Of paramount importance in limiting 
the past presentation of theater television 



142 



August 1952 Journal of the SMPTE Vol. 59 



programs has been the unavailability of 
adequate AT&T facilities to network 
theaters. The placement of theater 
television installations necessarily has 
been made along the routes of the coaxial 
cable and microwave relay facilities of 
AT&T. Most theaters in the country 
cannot be serviced by present telephone 
company facilities. This situation has 
forced theater circuits to make multiple 
installations in fewer cities, thus imped- 
ing theater television's early growth. 
Moreover, the lack of adequate AT&T 
long lines to theaters located on the cable 
and relay highways has impaired theater 
television's ability to develop regular 
program schedules. 

Here is a concrete example of the 
theater television distribution problem. 
At the beginning of the year, TNT pro- 
jected a series of nine programs, to be 
presented between March 3 and April 1 3. 
Considerable work went into the formu- 
lation of this series, which included an 
opera, a Broadway musical, a famous 
Broadway stage show, a championship 
fight, championship basketball tourna- 
ments, and other sports events. TNT 
requested AT&T clearances for each 
program to installed theaters in 23 metro- 
politan areas at the beginning of Febru- 
ary, requiring replies in time for effectu- 
ating the schedule. 

The total number of long lines clear- 
ances for cities requested by TNT of 
AT&T for these programs was 207; 
AT&T did not assure clearance of 151; 
thus 73% of theater television's require- 
ments were not fulfilled for the TNT 
spring schedule. 

The lack of AT&T long lines made this 
program schedule impractical. Not all 
theater television requests have met with 
this fate. However, this experience 
pointed up acutely that the telephone 
situation has been a difficult road block 
to the rapid growth of theater television, 
and that AT&T has not added sufficient 
distribution facilities for theater tele- 
vision. The telephone companies have 
shown increasing understanding of the 



theater television facilities needs. As a 
result, it is anticipated that AT&T will 
free more facilities for theater television, 
thereby speeding the growth of the me- 
dium and increasing its own returns in 
this field. In this direction, the de- 
velopment of more reasonable telephone 
charges for theater television should be 
high on the agenda. 

The FCC proceedings on theater tele- 
vision channels will center attention on 
practical alternatives to these facilities 
problems. Although postponed in the 
wake of the hectic activities surrounding 
the lifting of the television freeze, it is 
expected that the FCC will reschedule 
the theater television hearings as soon as 
possible. Meanwhile, theater television 
must and will continue to move forward. 

Problems on the road to the future are 
being solved already. Every month the 
number of theater television installations 
increases, thus reducing the cost factors 
for individual theaters. Currently, there 
are a dozen theater television installa- 
tions being made, including those of 
United Paramount Theatres, Warner 
Brothers Theatres and RKO Theatres. 
Valuable experience in pricing has been 
gained already. Programs are being 
formulated by TNT for production. And 
it is hopeful that intercity and intracity 
telephone facilities will become increas- 
ingly available at reasonable rates. 

Theater television will add fine enter- 
tainment of many kinds to its news and 
sports events. It will provide valuable 
services in the field of education, as well 
as specialized closed circuit services to 
government and industry. It is to be 
hoped that the growth timetable will not 
be prolonged by "faint heart" and "Let 
George do it" attitudes in the industry. 

The theater industry needs theater tele- 
vision. The public has already shown 
that it will go for it. Slowly simmering 
during the past period, theater television 
will erupt suddenly with its own formula 
for success in show business. The road 
may have obstacles but the future is 
bright. 



Nathan L. Halpern: Theater Television Progress 



143 



Proposed American Standard 
16mm Motion Picture Projector 
for Television 



J. HE INITIAL WORK on this proposal was 
done by an RMA Subcommittee, 
TR4.4.2, and a first draft was circulated 
in May 1950. Need for extensive re- 
vision was indicated at the final meeting 
of TR4.4.2 held in June 1 950. At about 
this time, the present Joint RTMA/ 
SMPTE Committee on Television Film 
Equipment was organized to replace the 
RMA Subcommittee. 

At the first meeting of the Television 
Film Equipment Committee, the pro- 
posal was again reviewed and revised 
and a second draft incorporating the de- 
sired changes was circulated in Septem- 
ber 1950. The extensive nature of the 
proposal precluded ready agreement, 
and a third draft, February 1951, and a 
fourth draft, May 1951, were required 
before the committee could reach final 
agreement. The latter was then sub- 
mitted independently to the RTMA and 
the SMPTE Standards Committee for 
further action. 

In the RTMA, the proposal TR4-4116 
was accepted by TR4, approved for 
circulation to industry by TREX and 



released as Standard Proposal #365 in 
June 1952. 

In the SMPTE, the Standards Com- 
mittee balloted on the question of 
approving Journal publication of the 
proposal for a 90-day period of trial and 
comment and, with but a few exceptions, 
voted affirmatively. The negative votes 
were based on the objection that the 
proposal was more of a procurement or 
performance specffication than a stand- 
ard defining required dimensional limits 
for the purpose of aiding interchange- 
ability. With the belief that publica- 
tion would stimulate worth-while dis- 
cussion, the Standards Committee gave 
the necessary approval in June 1952. 

Please send comments, in duplicate, 
to Henry Kogel, Staff Engineer, before 
December 15, 1952. If no adverse com- 
ments are received during the three- 
month trial period, the proposal will be 
submitted directly to ASA Sectional 
Committee PH22 with the recommenda- 
tion that it be processed as an American 
Standard. 



144 



August 1952 Journal of the SMPTE Vol.59 



Proposed American Standard 

16mm Motion Picture Projector 

For Use With Monochrome Television Film 

Chains Operating on Full-Storage Basis 

(Fourth Draft) 



PH22.91 



1. Scope 

1.1 This standard applies only to 16mm mo- 
tion picture projectors in which the film is ad- 
vanced intermittently. 

1.2 Projectors complying with this standard 
can be used only with film chains which oper- 
ate on a full-storage basis. 

1.2.1 In full-storage operation illumi- 
nation from the projector is restricted to 
the vertical retrace period of the tele- 
vision scan. 

1.3 Many of the characteristics of the pro- 
jector cannot be standardized in specific terms 
unless the pickup tube used in the film chain 
is specified. Since the Type 1 850-A iconoscope 
is used almost exclusively at present jn film- 
chain equipment, it has been used as the basis 
of standardization. If the projector is to be 
used with any other type of pickup tube, it will 
be necessary to modify the following para- 
graphs of this Proposed Standard: 2.1, 2.2, 
3.1, 3.2.1, 8.1 and all subparagraphs. 

2. Image Dimensions 

2.1 An image width of 4!/2 inches shall be 
considered standard. (See Paragraph 1.3.) 

2.2 The range of focus adjustment shall be 
sufficient to accommodate widths of image 
from 3% inches to 5 inches. (See Paragraph 
1.3.) 

2.2.1 The focusing operation shall not 
displace the picture by more than 1.0% 
of its width. 

3. Projection Lens 

3.1 Focal Length. In following sections, for 
test purposes, the use of a lens having a focal 
length of approximately 3 ] /2 inches will be 
assumed. (See Paragraph 1.3.) 



P. 1 of 8 pp. 

3.2 Resolution. 

3.2.1 Resolution shall be defined and 
measured in accordance with American 
Standard Z22.53-1946, except that 
measurement shall be made with the 
standard picture width. (See Paragraph 
1.3.) 

3.2.2 The resolution shall be at least 
80 lines per millimeter for the patterns 
identified as E and D and at least 90 
lines per millimeter for all others. 

4. Optical Axis 

4.1 The projector shall include, or have 
available as an accessory, a sturdy pedestal. 
Means shall be provided to place the optical 
axis (when level) at any required height from 
47 to 49 inches from the floor. 

4.2 A tilting mechanism shall be included 
although this need not permit either quick 
change or change during operation. The 
range of tilt shall be sufficient to raise or lower 
by 1 inch an image of standard width, pro- 
jected by a 3 ] /2-inch lens. 

4.3 A leveling mechanism capable of rotat- 
ing the projector about an axis parallel to the 
optical axis shall be included. 

5. Film Gate 

5.1 Dimensions. The dimensions of the pic- 
ture aperture and its location relative to the 
film shall be in accord with American Stand- 
ard Z22.8-1950. 

5.2 Lateral guiding. At the picture aperture 
the sprocket hole edge of the film shall be 
used for lateral guiding. (Note: This is an 
exception to the recommendations of Ameri- 
can Standard Z22.8-1950. For a discussion 
of the problem involved, see Note 3 of Z22.8.) 

NOT APPROVED 



August 1952 Journal of the SMPTE Vol. 59 



145 



Proposed American Standard 

16mm Motion Picture Projector 

For Use With Monochrome Television Film 

Chains Operating on Full-Storage Basis 

(Fourth Draft) 



PH22.91 



6. Framing Device 

6.1 The projector shall have a readily ac- 
cessible means for positive framing of the pic- 
ture when the projector is in operation. The 
range of the framing mechanism shall extend 
0.025 inches above and below the standard 
position measured at the film. The framing de- 
vice shall be free from creep during operation. 

6.2 The method employed for framing shall 
not change the position of the projected image 
of the picture aperture by more than 1.0% of 
the picture width over the full framing range. 

7. Picture Stability 

7.1 Definition. 

7.1.1 The stability of the image de- 
pends upon the ability of the projector 
to locate succeeding frames of film in 
exactly the same position relative to the 
picture aperture. Failure to perform this 
function perfectly results in either jump 
(vertical instability) or weave (horizontal 
instability) or both. 

7.1.2 Jump and weave shall be meas- 
ured in terms of the peak-to-peak ex- 
cursions observed. In each case the 
result shall be stated as a percentage 
of picture width. 

7.2 Standard. 

7.2.1 Jump shall not exceed 0.2% of 
picture width. 

7.2.2 Weave shall not exceed 0.15% 
of picture width. 

7.3 Method of measurement. 

7.3.1 Since jump and weave are 
mechanical characteristics of the pro- 
jector and are independent of image 
magnification, it is recommended that 
both be measured with the greatest 
magnification that will still give a suffi- 



P. 2 of 8 pp. 

ciently bright image for direct observa- 
tion. 

7.3.2 Jump and weave are usually 
measured by projecting a Steady Test 
Film which has an extra perforation in 
the center of the picture area. This test 
perforation is made in the same opera- 
tion in which the sprocket holes are 
made and it is very precisely located 
with respect to the sprocket holes. Film 
of this type may be obtained from the 
Society of Motion Picture and Television 
Engineers. 

8. Image Illumination 

8.1 Intensity. There is no evidence to indi- 
cate that any particular significance should 
be attached either to the peak value of the 
illumination or to the exact shape of the light 
pulse as a function of time. Consequently, only 
the time average value of illumination in- 
tensity is standardized. However, in full-stor- 
age operation the duration of the light pulse 
will be approximately 5% of the period of a 
television field. This short duty cycle is likely 
to introduce large measurement errors unless 
certain precautions are observed. (See Para- 
graph 1.3.) 

8.1.1 Definition. The intensity of illum- 
ination will be measured in Iconoscope 
Exposure Units (abbreviated IEU). The 
IEU is analogous to the foot-candle. Just 
as foot-candles are measured by a de- 
tector having a spectral sensitivity simi- 
lar to that of the human eye, so are lEU's 
measured by a detector having a spec- 
tral sensitivity similar to that of the Type 
1850-A iconoscope. For illumination 
from a blackbody radiator at a color 
temperature of 2700 K, a foot-candle 



NOT APPROVED 



146 



August 1952 Journal of the SMPTE Vol. 59 



Proposed American Standard 

16mm Motion Picture Projector 

For Use With Monochrome Television Film 

Chains Operating on Full-Storage Basis 

(Fourth Draft) 



PH22.91 



meter and an IEU meter will give identi- 
cal readings. (See Paragraph 1.3.) 

8.1.2 Standard. The intensity of illumi- 
nation shall be at least lEU'S.* 
(See Paragraph 1 .3.) 

8.1.3 Method of measurement. 

8.1.3.1 The intensity of illumi- 
nation shall be measured in the 
plane of the standard image 
with the detector in the central 
area of the image. (See Para- 
graph 1.3.) 

8.1.3.2 The detector shall have 
a spectral sensitivity matching as 
closely as possible the spectral 
sensitivity of the Type 1850-A 
iconoscope. A sufficiently close 
approximation is afforded by a 
Weston Photronic Cell, Model 
594RB, equipped with a Corning 
filter, Type 5-51, 5562. (See 
Paragraph 1.3.) 

8.1.3.3 The meter used with 
the Photronic Cell shall have a 
resistance of 20 ohms or less. 
Because the illumination pulse is 
of short duration and high peak 
intensity, the resistance of the 
meter will cause errors in meas- 
urement which increase rapidly 
with resistance value. For a 20- 
ohm movement, the error will 
not exceed 2% over the antici- 
pated range of intensities with 
the Weston Model 594RB cell. 
(See Paragraph 1.3.) 

Field experience relating illumination in lEU's to 
satisfactory quality is as yet quite limited. It has 
not yet been possible to determine the number of 
lEU's which represent the line of demarcation be- 
tween satisfactory and unsatisfactory performance. 



P. 3 of 8 pp. 

8.1.3.4 The combination of 
meter and cell shall be cali- 
brated against a foot-candle 
standard using a blackbody 
source of illumination at 2700 K. 
(See Paragraph 1.3.) 
8.1.4 The source of illumination shall 
be operated within any applicable rat- 
ings established by the manufacturer of 
the source. 

8.2 Control of Intensity. It is probable that 
means for varying the intensity of illumination 
will be required for certain types of pickup 
tube. However, present information is not suf- 
ficent to permit the formulation of a standard. 

8.3 Uniformity. 

8.3.1 Intensity of illumination at any 
point in the area of the standard image 
shall be not less than 80% of the maxi- 
mum intensity of illumination. 

8.3.2 Upon replacement of an incan- 
descent projection lamp, if such is used, 
no readjustment shall be required to 
achieve this distribution. 

8.3.3 The receptive area of the light- 
sensitive element used for these readings 
shall have a diameter not greater than 
5% of the picture width. No reading 
shall be taken with the center of the re- 
ceptive element closer to the edge of 
the image area than 5% of the picture 
width. 

8.4 Color. Although color of illumination 
may have significant effects on picture qual- 
ity, present knowledge is not sufficient to per- 
mit the formation of a standard. 

8.5 Flicker. Variation from pulse to pulse of 
the time integral of the illumination falling on 
any small area of the image may, under some 
conditions, give rise to visible flicker in the pic- 

NOT APPROVED 



August 1952 Journal of the SMPTE Vol. 59 



147 



Proposed American Standard 

16mm Motion Picture Projector 

For Use With Monochrome Television Film 

Chains Operating on Full-Storage Basis 

(Fourth Draft) 



PH22.91 



ture from the film chain. However, present 
knowledge is not sufficient to permit the for- 
mulation of a standard. 
8.6 Illumination Period. 

8.6.1 Definition. 

8.6.1.1 The illumination period 
is the interval of time in which 
the instantaneous intensity of il- 
lumination in any part of the 
image area exceeds 10% of the 
peak instantaneous intensity. 

8.6.1.2 The length of the illum- 
ination period shall be stated in 
terms of a percentage of V, 
where V is the time from the 
start of one television field to the 
start of the next field. 

8.6.2 Standard. The illumination pe- 
riod shall not exceed 5% of V. This 
value is dictated by the presently ac- 
cepted minimum value for the vertical 
blanking period of the television system, 
which is 5% of V. 

8.6.3 Method of measurement. The il- 
lumination period shall be measured by 
means of a photocell, an amplifier, an 
oscilloscope and a timing oscillator. The 
photocell and amplifier must respond 
without saturation to the peak intensity 

encountered and the frequency response 
of the combination shall be down not 
more than 3 db at 50 kc. 

9. Pull-Down Period 

9.1 Definition. The pull-down period is the 
interval of time in which film is moving through 
the picture aperture. 

9.2 Standard. The only restriction to be 
placed on the pull-down period is that it shall 



P. 4 of 8 pp. 

never overlap any part of the illumination 
period. 

9.2.1 If, in a particular mechanism, 
there is any possibility that the pull- 
down period may vary in phase relative 
to the illumination period, then the 
mechanism shall be designed to allow 
this phase to change by 3% of V from 
the optimum position with no overlap of 
the two periods. 

9.3 Method of measurement. The existence 
of overlap may be detected by projecting a 
test subject consisting of sharply defined white 
objects on a black background, and inspect- 
ing the projected picture for evidence of travel 
ghost. For this test, film complying with the re- 
quirements of American Standard Z22.54- 
1946 is recommended, although many title 
strips will be found quite satisfactory. 

10. Phasing of Projector Relative to 
TV Vertical Scan 

10.1 For the case of a fixed relation be- 
tween pull-down and illumination periods: 

10.1.1 Means shall be provided for 
setting the illumination period in any 
desired phase relative to the 60-cycle 
frequency which controls the phase of 
the motor. 

10.1.2 Each time the projector is 
turned on, it shall re-establish this pre- 
selected phase relation by fully auto- 
matic means in less than 3 seconds. 

10.1.3 During operation, the pre- 
selected phase relation shall be main- 
tained within '/2% of V. 

10.2 For the case of the illumination period 
locked to the vertical synchronizing signal and 
independent of the pull-down period, means 
shall be provided for insuring compliance with 
Paragraph 9.2 of this Proposed Standard. 



NOT APPROVED 



148 



August 1952 Journal of the SMPTE Vol. 59 



Proposed American Standard 

16mm Motion Picture Projector 

For Use With Monochrome Television Film 

Chains Operating on Full-Storage Basis 

(Fourth Draft) 



PH22.91 



P. 5 of 8 pp. 



11. Film Capacity and Reel Tension 

11.1 The projector shall accommodate reels 
of any capacity from 400 to 3600 feet which 
comply with the requirements of Proposed 
American Standard PH 22.1 1-1952. 

1 1 .2 For any reel size in this range, the take- 
up tension shall at no time be less than 3 
ounces nor greater than 10 ounces (hub 
diameters less than 4.5 inches excepted). 

11.3 For any reel size in this range, the 
braking mechanism on the feed reel shall not 
cause a tension greater than 3 ounces (hub 
diameters less than 4.5 inches excepted). 

12. Film Life 

12.1 After 100 passages through the projec- 
tor mechanism, film shall exhibit no evidence 
of damage either visible in the projected pic- 
ture or audible in the reproduced sound sig- 
nal. 

12.2 In order that a loop of film may be 
used in this test, renewal of the splice as many 
times as may be necessary is permitted. 

12.3 The film used in this test may and 
should be carefully selected and lubricated. 
The projector is not required to pass this test 
with film which is in inferior condition. 

12.4 Passage of a splice in good condition 
through the mechanism shall not cause serious 
disturbance, such as loss of loop, nor shall the 
mechanism cause excessive damage to the 
splice. 

13. Starting Time 

13.1 Definition. The interval between appli- 
cations of power and the attainment of: (a) 
synchronous operation of the motor and (b) a 
flutter content in the sound output which is less 
than the maximum specified in Paragraph 
17.2. 



13.2 Standard. The starting time shall not 
exceed 5 seconds. 

14. Film Speed 

14.1 The nominal speed of projection shall 
be 24 frames per second. This shall not be 
interpreted as excluding the use of a 3-2 
mechanism. 

15. Stopping Distance 

15.1 Definition. The length of film that 
passes through the film gate after removal of 
power. 

15.2 Standard. The stopping distance shall 
not exceed 3 feet. 

16. Manual Drive 

16.1 Some readily accessible means shall 
be provided for slow-speed manual operation 
of the mechanism as a check on threading, etc. 

17. Sound) Scanning System 

17.1 Synchronization. The film path dis- 
tance measured in the direction of travel from 
the center of the picture aperture to the point 
to which sound scanning occurs shall be 26 
frames Vi frame. 

1 7.2 Mechanical stabilization. The rms value 
of the total (sum of all frequencies) flutter shall 
not be greater than 0.25% when using a 
3000-cycle flutter test film complying with vhe 
requirements of American Standard Z22.43 
1946. Film splices shall not cause any serious 
disturbance in sound stabilization. 

17.3 Dimensions of Scanning Aperture. In 
the plane of optimum focus the scanning light 
beam shall have a maximum width of 0.0005 
inches and a length of 0.071 0.001 inches. 
(Reference for length: American Standard 
Z22.41-1946.) 



NOT APPROVED 



August 1952 Journal of the SMPTE Vol. 59 



149 



Proposed American Standard 

16mm Motion Picture Projector 

For Use With Monochrome Television Film 

Chains Operating on Full-Storage Basis 

(Fourth Draft) 



PH22.91 



17.4 Adjustment of Scanning Beam. 

17.4.1 Lateral Adjustment. Means 
shall be provided for adjusting the 
lateral position of the scanning beam 
such that the projector does not repro- 
duce either signal on a buzz-track test 
film complying with the requirements 
of American Standard Z22.57-1947. 

17.4.2 Azimuth Adjustment. 

17.4.2.1 Means shall be pro- 
vided for adjusting the azi- 
muth of the scanning beam. 

17.4.2.2 The azimuth shall 
be adjusted to secure maxi- 
mum response using a 7000- 
cycle test film complying with 
the requirements of American 
Standard Z22.42-1946. 

17.4.3 Focus Adjustment. 

1 7.4.3.1 Means shall be pro- 
vided for adjusting the focus 
of the sound optics to place 
the plane of optimum focus in 
coincidence with the emulsion 
plane. 

17.4.3.2 Focus shall bead- 
justed to secure maximum re- 
sponse using a test film com- 
plying with the requirements of 
American Standard Z22.42- 
1946. 

1 7.4.3.3 Means shall be pro- 
vided for rapidly and accu- 
rately shifting the plane of 
optimum focus to coincide with 
the emulsion position on either 
side of the film. 

1 7.5 Light Distribution. The light distribution 
in the scanning aperture shall be sufficiently 
uniform to produce a signal across a resistive 



P. 6 of S pp. 

load at the output of the preamplifier which is 
constant within 1.5 db when reproducing a 
Scanning Beam Uniformity Test Film comply- 
ing with the requirements of American Stand- 
ard Z22.80-1950 or Z22.81-1950. 
17.6 Exciter Lamp. 

17.6.1 The exciter lamp shall be so 
mounted as to permit rapid replace- 
ment. 

17.6.2 It is not desirable that uni- 
formity of illumination in the scanning 
aperture be critically dependent upon 
exciter lamp position. If this condition 
exists, means shall be provided for in- 
dependent horizontal and vertical ad- 
justment of the exciter lamp position. 

17.6.3 The exciter lamp shall be a 
prefocused type unless the lamp holder 
is a replaceable type equipped with 
adequate adjustments which can be 
preset, and a spare lamp holder is pro- 
vided. 

1 7.6.4 The exciter lamp shall be op- 
erated at all times within any appli- 
cable ratings established by the manu- 
facturer of the lamp. 

18. Sound Amplification System 

Any statement of sound-reproduction charac- 
teristics must necessarily cover the perform- 
ance of a preamplifier which is specifically 
designed as a component of the projector. 
However, it is not essential that all or even any 
part of the preamplifier be included in the pro- 
jector structure. Wherever they are mounted, 
all parts of the preamplifier should be readily 
accessible. 

18.1 Output Impedance. There shall be 
available output impedances of 600 and 150 
ohms, both to be balanced outputs. 



NOT APPROVED 



150 



August 1952 Journal of the SMPTE Vol. 59 



Proposed American Standard 

16mm Motion Picture Projector 

For Use With Monochrome Television Film 

Chains Operating on Full-Storage Basis 

(Fourth Draft) 



PH22.91 



1 8.2 Output Level. 

18.2.1 Standard. The output level 
shall be -lOdbm. 

1 8.2.2 Method of measurement. This 
level shall be produced using level test 
film complying with the requirements 
of American Standard Z22.45-1946. 

18.2.3 A gain normalization control 
shall be provided having sufficient 
range to insure compliance with the 
above standard for any normal com- 
bination of exciter lamp, photocell and 
amplifier tubes. 

18.3 Frequency Response. 

1 8.3.1 If the frequency response from 
film to output is fixed, it shall be flat 
within 1 db from 50 to 6000 cycles 
per second. If tone controls are pro- 
vided in the preamplifier, their range 
of adjustment shall include this re- 
sponse. 

18.3.2 Method of measurement. The 
frequency response shall be determined 
by means of a multifrequency test film 
complying with American Standard 
Z22.44-1946. The amplitude of re- 
sponse shall be measured across a re- 
sistance load at the output of the pre- 
amplifier. The frequency response shall 
be determined with standard gain. 
(See Paragraph 18.2.) 

18.4 Distortion. Although it is desirable to 
state a distortion standard which will cover 
the photocell as well as the preamplifier, a 
method of measurement which will accomplish 
this result is not known. Consequently, the 
present Standard Proposal covers only distor- 
tion in the preamplifier. 



1 8.4.1 Standard. Total harmonic dis- 
tortion in the preamplifier at standard 
output level shall not exceed !/2% in 
the range from 50 to 6000 cycles per 
second. 

1 8.4.2 Method of Measurement. Test 
signals from an oscillator shall be ap- 
plied at the photocell input of the pre- 
amplifier and distortion shall be meas- 
ured with a distortion analyzer at the 
preamplifier output at standard output 
level. 

1 8.5 Preamplifier Noise Level. 

18.5.1 Standard. The noise level of 
the preamplifier shall be 65 dbm. 

1 8.5.2 Method of measurement. The 
noise level of the preamplifier shall be 
measured at standard gain (see Para- 
graph 18.2), with the projector run- 
ning, the exciter lamp energized and 
no light entering the photocell. 

18.6 Overall Noise Level. 

18.6.1 Standard. The overall noise 
level shall be -55 dbm. 

1 8.6.2 Method of Measurement. The 
overall noise level shall be measured at 
standard gain (see Paragraph 18.2), 
with the projector running, the exciter 
lamp energized and'no film in the ma- 
chine. 

Appendix A 

The gate of the projector should be designed 
to provide easy access to aperture and rails 
for thorough and effective cleaning and in- 
spection. 



NOT APPROVED 



August 1952 Journal of the SMPTE Vol. 59 



151 



Proposed American Standard 

16mm Motion Picture Projector 

For Use With Monochrome Television Film 

Chains Operating on Full-Storage Basis 

(Fourth Draft) 



PH22.91 



P. of 8 pp. 



Appendix B 

The American Standards listed below have 
been cited in the present Proposed Standard. 
Copies of any of the reference standards may 
be obtained from the American Standards 
Association, 70 East 45 Street, New York 17, 
New York. 

1. Z22.8-1950 

Location and Size of Picture Aperture 
of 16mm Motion Picture Projectors. 

2. PH22.11-1952 

16mm Motion Picture Projection Reels. 

3. PH22.16 

Emulsion and Sound Record Positions 
in Projector for Direct Front Projection 
of 16mm Sound Motion Picture Film. 

4. Z22.41-1946 

Sound Records and Scanning Area of 
16mm Sound Motion Picture Prints. 

5. 222.42-1946 

Sound-Focusing Test Films for 16mm 
Sound Motion Picture Projection Equip- 
ment. 

6. Z22.43-1946 

3000-Cycle Flutter Test Film for 1 6mm 
Sound Motion Picture Projectors. 



7. Z22.44-1946 

Multi-Frequency Test Film for Field 
Testing 16mm Sound Motion Picture 
Projection Equipment. 

8. Z22.45-1946 

400-Cycle Signal Level Test Film for 
16mm Sound Motion Picture Projection 
Equipment. 

9. Z22.53-1946 

Method of Determining Resolving 
Power of 16mm Motion Picture Projec- 
tion Lenses. 

10. Z22.54-1946 

Freedom from Travel Ghost in 16mm 
Motion Picture Sound Reproducers. 

11. Z22.57-1947 

Buzz-Track Test Film for 16mm Motion 
Picture Sound Reproducers. 

12. Z22.80-1950 

Scanning-Beam Uniformity Test Film 
for 16mm Motion Picture Sound Repro- 
ducers (Laboratory Type). 

13. Z22.81-1950 

Scanning-Beam Uniformity Test Film 
for 16mm Motion Picture Sound Re- 
producers (Service Type). 



NOT APPROVED 



152 



August 1952 Journal of the SMPTE Vol. 59 



Proposed Amendments to the Bylaws 



TWO SUGGESTED AMENDMENTS to the Bylaws 

of the Society are presented here, with the 
Board of Governors' reasons for proposing 
that they be adopted. They represent the 
first formal result of an official study of 
organization and operating practices of 
SMPTE started last January at the Board's 
request and are intended to state clearly 
two matters of importance. The first re- 
cites the long established policy of the 
Society respecting the voluntary nature of 
Standards and Recommendations de- 
veloped within SMPTE engineering com- 
mittees. The second sets down, of legal 
necessity, a newly drawn provision for dis- 
position of the Society's assets in the un- 
likely event of dissolution. 

For these amendments to become official 
they must be processed as outlined in By- 
law XIII last published on page 348 of the 
Journal for April this year. The Board of 
Governors initiated the recommendation 
during its meeting in New York on July 17. 
Publication here is also required and next 
comes consideration by the voting members 
during the regular meeting of the Society 
which is held annually during the fall con- 
vention. This year it will occur at 3 P.M. 
Monday afternoon, October 6, just pre- 
ceding the first technical session of the 
Society's 72d Convention at the Hotel 
Statler in Washington, D.G. 

Voluntary Standards 

As a part of his regular quarterly report 
to the Board of Governors, Fred T. Bow- 
ditch, Engineering Vice-President, stated 
his belief that although the members of the 
Society knew that American Standards for 
which the Society serves as sponsor, and 
other formal Recommendations published 
by the Society, were voluntary, and that 
their existence did not preclude members or 
nonmembers from manufacturing and sell- 
ing products not conforming to the Stand- 
ards, it would be advisable to incorporate a 
provision to that effect in the Bylaws of the 



Society. The Board was in agreement and 
passed a Resolution proposing adoption of 
the following: 

BYLAW XIV 

Standards and Recommendations 

Sec. 1. American Standards sponsored 
by the Society and the Society's Recom- 
mendations are proposed and adopted in 
the public interest and are designed to 
eliminate misunderstanding between the 
manufacturer and the purchaser and to 
assist the purchaser in selecting and ob- 
taining the proper product for its particular 
need. Existence of such a Standard or 
Recommendation does not in any respect 
preclude any member or nonmember from 
manufacturing or selling products not con- 
forming to the Standard or Recommenda- 
tion. 

Disposition of Assets 

Herbert Barnett, Executive Vice-Presi- 
dent, who served as Chairman in the ab- 
sence of President Peter Mole, stated that in 
his opinion it would be advisable to provide 
in the Bylaws for disposition of the Society's 
assets in case of dissolution. After ex- 
tended discussion, the Board voted in favor 
of such a provision, approving unanimously 
the following proposed amendment : 

BYLAW XV 

Disposition of Assets and Dissolution 

Sec. 1. Upon the dissolution of the 
Society and after payment of all indebted- 
ness of the Society, the funds, investments 
and other assets of the Society shall be 
given and transferred to some other non- 
profit organization having objects similar 
to those of the Society. The selection of 
such other organization shall be made by 
the Board of Governors either at a regular 
meeting of said Board of Governors or at a 
special meeting of said Board called for the 
purpose of selecting such an organization. 



August 1952 Journal of the SMPTE Vol. 59 



153 



72d Semiannual Convention 



This Fall's Convention at the Hotel Statler, Washington, D.C., October 6-10, will be 
a blaze of highlights with very strong base lighting of the fields of Society interest, for de- 
spite the heat, humidity, politics and other summer distractions all the plans keep building . 

Program Chairman Joe Aiken has lined up the scores of papers into some 14 sessions 
to release the Advance Notice of the Convention to be mailed to all members in the 
Western Hemisphere on August 6. This carries the tear-off postal for reserving hotel 
rooms. If you have not made reservations and need a copy of the postal for convenience, 
ask Society headquarters for one. The Advance Notice also has the abstract of the 
technical papers sessions. 

Although the sessions are all arranged, occasionally authors have to withdraw a paper 
so if you have a special paper suddenly cleared, it might still be fitted into the Final Pro- 
gram. If so, write air mail or wire: Joseph E. Aiken, 116 N. Galveston St., Arlington, 
Va. 

One large and special part of the technical program will be the first International Sym- 
posium on High-Speed Photography which is planned as fully the equivalent of two days 
of sessions, some of them concurrent with sessions on topics from other parts of the Soci- 
ety's interest. John H. Waddel is Chairman for this symposium. 

16mm equipment maintenance is the subject of another session being developed by 
R. T. Van Niman who will welcome all who come bearing manuscripts, ideas or possibly 
other contributions to this symposium and discussion. 

A session on magnetic striping has been organized by Glenn Dimmick. This session 
contains four formal papers but there is still allowable room for anyone who feels that he 
can or should make a contribution to this subject. 

Highlights that can now be mentioned are : descriptions of recording television pic- 
tures on magnetic tape presentation of the Signal Corps' Mobile Television System; 
report on the National Television Systems Committee accomplishments in color television; 
laboratory session papers on high-speed processing, rapid drying, and butt-weld splicing. 

Bill Kunzmann, the Society's Convention Vice-President, gave the Board of Governors 
a complete report in July, covering all the arrangements and commitments made for the 
Washington convention. Bill was in Washington in late May and at that time held an 
organizational meeting which resulted in our having the following roster of folks who will 
put over the operation of the convention : 

Program Chairman Joseph E. Aiken 

International Symposium on High-Speed Photography John H. Waddell 

Papers Committee Chairman, Edward S. Seeley Vice-Chairmen, Joseph E. Aiken, 
Fred G. Albin, Geo. W. Colburn, Gerald G. Graham, W. H. Rivers and John H. 
Waddell 

Local Arrangements Joseph E. Aiken 

Hotel Reservations and Transportation Henry Fisher 

Luncheon and Banquet Nathan D. Golden 

Membership and Subscriptions Ray Gallo, assisted by G. J. Badgley 

Motion Pictures James Frank, Jr., assisted by John V. Waller 

Naval Ordnance Laboratory Session Arrangements Max Beard 

Projection, 35mm and 16mm Carl R. Markwith and Henry F. Heidegger, assisted by 
John V. Waller, and members Local 224, I.A.T.S.E. 

Public Address and Recording J. Clinton Greenfield 

Publicity Harold Desfor, assisted by Leonard Bidwell and J. A. Moses 

Registration and Information Keith B. Lewis, assisted by P. M. Cowett, Fred W. Gar- 
retson, Max Kerr, J. A. Moses and Howland Pike 

Television Col. C. S. Stodter, R. N. Harmon and W. P. Button 

Ladies Reception and Registration Mrs. N. D. Golden and Mrs. J. E. Aiken, Co- 
hostesses 



154 






Engineering Activities 



Development of American Standards 

Motion picture and related tele- 
vision standards in the United States are 
today developed primarily by SMPTE En- 
gineering Committees. While that is wide- 
spread knowledge, the steps in that develop- 
ment are probably not so well known. A 
brief review of the procedures used in produc- 
ing American Standards in cinematography 
is therefore given below. It is hoped that an 
awareness of these procedures will make for 
an even wider participation in standards 
activity, which can only serve to improve 
the quality and observance of these stand- 
ards. 

1. Request for Standard: The need for 
a standard may be brought to the attention 
of the Society's Engineering Vice-President 
by anyone interested: manufacturer, con- 
sumer, Society member, government body, 
etc. 

2. Drafting the Standard: The Engi- 
neering Vice-President estimates the gen- 
eral value of the request and refers the 
project to the appropriate Engineering 
Committee. The Committee, a broad 
representative group of some phase of the 
motion picture industry, makes any re- 
quired studies or surveys and prepares a 
draft standard. 

3. Reviewing the Standard: After the 
Engineering Committee approves its 
"final" draft, the proposed standard goes 
through an extensive review to assure the 
kind of acceptance required under our 
system of voluntary standards. 

a. Standards Committee: The SMPTE 
Standards Committee is composed, in the 
main, of the chairmen of the engineering 
committees. This first review of the pro- 
posal is therefore designed to achieve agree- 
ment within the Society. Approval by the 
Standards Committee is required before the 
draft can be published in the Journal. 

b. Journal Publication: Publication of the 
draft for some stated period (usually 3 
months) for trial and comment provides all 
Journal readers an opportunity to study and 
criticize the proposal. 

c. ASA Sectional Committee, PH22: If no 
adverse comments have been received dur- 
ing the trial period, the Engineering Vice- 
President transmits the proposed standard 



to PH22 with a recommendation that it be 
processed as an American Standard. 
PH22 is composed of representatives from 
every group having a vital interest in cine- 
matographic standards. Approval by 
PH22 generally indicates that the technical 
content of the standard is in good order. 

d. SMPTE Board of Governors: After 
approval, PH22 returns the standard to the 
Society for sponsor approval which is con- 
ferred by Board of Governors action. 

e. Photographic Standards Correlating Com- 
mittee: At this point and on behalf of the 
Board of Governors, the Executive Secre- 
tary formally transmits the proposed 
standard to the Director of the ASA, con- 
cluding Society action on that particular 
standard. The Correlating Committee is 
an ASA body formed to integrate the 
standards activity of all elements of the 
photographic industry and so reviews all 
photographic standards proposals before 
final approval is granted. 

4. American Standard: A proposed 
standard acquires the stamp "American 
Standard" upon approval of the ASA 
Standards Council, the final board of re- 
view. This group has representatives from 
each ASA Member Body and thus provides 
a clearing house for vast numbers of stand- 
ards from widely diversified industries. 
Publication in the SMPTE Journal com- 
pletes the lengthy journey from request to 
American Standard. 

It should be noted that any group may 
submit a proposed standard to PH22 for 
processing as an American Standard and 
this the Motion Picture Research Council 
has done in quite a few instances. This in 
no way changes the ensuing procedure 
since the SMPTE as sponsor of PH22 must 
review the proposal in order to authorize 
the required sponsor approval. 

Your attention is also drawn to the fact 
that the technical committees of the 
Society are not closed corporations. A 
request to have your organization repre- 
sented on one or several engineering com- 
mittees would be welcomed by the Engi- 
neering Vice-President and would receive 
serious consideration Henry Kogel, Staff 
Engineer. 



155 



Canadian Standards Association 



The Canadian Standards Association was 
established by Dominion charter granted 
in 1919. As a result of experience gained 
during several years of operation and 
particularly during the war years the 
charter was amended in 1944 to embrace 
a broader field of operation as outlined 
below: 

(a) To provide, originate and furnish 
Canadian standards of any nature what- 
soever which are in the interests of pro- 
ducers and users; to coordinate the efforts 
of producers and users toward the improve- 
ment and standardization of materials, 
processes and related matters; to provide 
systematic means by which organizations 
interested in standardization work may 
cooperate in establishing and promoting 
Canadian standards to the end that 
duplication of work and the promulgation 
of conflicting standards may be avoided. 

(b) To serve as a clearing house for 
information on standardization work in 
Canada and foreign countries; to further 
the standardization movement as a means 
of advancing the national economy, and to 
promote a knowledge of, and the use of, 
approved Canadian standards both in 
Canada and foreign countries; to act as 
an authoritative Canadian channel in 
international cooperation in standardiza- 
tion work. 

(c) To register in the name of the 
Association, and to hold, own, use and 
operate any and all trade marks, proof, 
letter or device and to enforce and protect 
the use of such marks, proofs, letters or 
devices and to oppose any proceedings or 
applications which may seem calculated 
directly or indirectly to prejudice the 
interests of the Association. 

Committee Organization 

The Canadian Standards Association 
has close contact, by direct representation, 
with the following classifications of interest : 
Manufacturers, Departments of the Do- 
minion Government, Provincial Govern- 
ments, Public Utilities, Educational Insti- 
tutions, Professional Bodies, Labour Or- 
ganizations, Purchasing Departments, In- 
surance Interests. 

From the various classifications of in- 
terest a series of Divisions has been estab- 



lished covering such representative fields 
as Textiles, Agriculture, Pulp and Paper, 
Steel Construction, Electrical Engineering, 
etc. From these Divisions a Main Com- 
mittee is drawn, each member serving for 
a period of three years and eligible for 
further service at the discretion of the 
nominating interests. This is the govern- 
ing body of the C.S.A. 

From the Main Committee, members 
are elected by the Divisions to form the 
Executive Committee which is the ad- 
ministrative body of the Association. 

Sectional committees are appointed by 
the Divisions, each sectional committee 
consisting of from 10 to 30 members, 
representing the best available knowledge 
and experience in their respective fields. 
Their responsibility is to supervise the 
work of standardization with the scope of 
each division. They are responsible for 
the approval of specifications, which have 
been developed by their working com- 
mittees and for submitting same to the 
Executive Committee for final approval 
and publication. 

When a request is received to produce 
a standard specification for any commodity, 
it is referred to the division interested, 
for consideration and recommendation to 
the Executive Committee for action. 
Should there appear to be a reasonable 
demand for the standard in question and 
sufficient information available to assure 
satisfactory completion of the work, 
authority will be given to the division by 
the Executive Committee to proceed with 
the preparation of a standard. 

If sufficient information appears to be 
lacking, and scientific investigation is 
considered necessary, proposals will be 
made to a recognized research body, 
such as the National Research Council, 
to conduct tests or make investigations 
in order to provide needed information 
that will permit an authoritative standard 
to be prepared. 

These Working Committees consist of j 
a variable number of members ranging i 
from five or six to as high as thirty or more, j 
depending on the nature of the work to be 
done. 

As work progresses, a draft specification 
is prepared and subsequently discussed 



156 



at meetings of the Working Committee. 
Verbal recommendations for revision, 
and those received from members unable 
to attend or interests not desiring direct 
representation, receive full consideration. 
This usually necessitates the preparation 
of several draft specifications, requiring 
considerable time before a proposed stand- 
ard is considered ready for publication. 

Every effort is made, not only to assure 
full representation of the views of all 
interests, but to tap every available source 
of information, both foreign and domestic. 
Accordingly, when a standard is published, 
it represents, as far as possible, the best 
available authority consistent with general 
knowledge and local conditions. 

Approvals Division 

The G.S.A. has had a certification pro- 
cedure in effect for many years and the 
C.S.A. label is recognized throughout 
Canada as a symbol of assurance that 
electrical equipment and devices are 
reasonably free from fire and accident 
hazards. This Approval Service, which 
now insures compliance with safety and 
performance standards can be extended, 
as and when industry becomes convinced 
that certification, on a quality basis, is 
beneficial to the producer as well as to the 
consumer. The details of the procedure 
will be developed in collaboration with 
appropriate producer and consumer in- 
terests as required. 

C.S.A. Standards 

An important feature of G.S.A. stand- 
ards, in line with British and American 
standardizing practice, is that they are 
"voluntary" standards. As such, they 
serve as recommendations to industry 
and may or may not be adhered to by the 
manufacturers concerned. 

Such standards may, on the other hand, 
become mandatory by adoption by a 
government department having legal au- 
thority to enforce their requirements in 
the matters of governmental purchases, 
when the standards concern specific ma- 
terials or products. The Association has 
published approximately 200 such stand- 
ards thus far limited to the various 
sections of engineering. 

Photography 

The G.S.A. Sectional Committee on 
Photography was organized in 1948 with 



Dr. L. E. Howlett of the National Re- 
search Council as chairman. Three speci- 
fication committees are at work in this 
field at the present time: 

Z7.1 Motion Picture Photography; 
Z7.2 Still Photography; and 
Z7.3 Survey Photography. 
Committee Z7.1 has completed a review 
of all basic A.S.A. and B.S.I, motion pic- 
ture standards and some 43 have been 
published by the C.S.A. A specification 
for an industrial and educational model 
16mm projector is now in the final draft 
stage. Members of this committee with 
their affiliations are: 
A. H. Simmons (Secretary), Gevaert 

(Canada) Limited, Ottawa 
Harold Walker, Dominion Sound Equip- 
ments Limited, Montreal 
Don Spring, Canadian Kodak Sales Ltd., 

Toronto 
John Gerald, Ansco of Canada Ltd., 

Toronto 
Sqn. Ldr. N. Drolet, Armed Services, 

Ottawa 
Gordon Adamson, National Film Society, 

Ottawa 
Gaudry DeLisle, Department of Education, 

Quebec City 

H. Goldin, Consulting Engineer, Toronto 
M. Metzger, Associated Screen News Ltd., 

Montreal 
Arthur Elsey, Canadian Industries Ltd., 

Montreal 
P. D. Carmen, National Research Council, 

Ottawa 
A. J. Pauley, The Odeon Theatres 

(Canada) Ltd., Toronto 

F. T. Myles, R.C.A. Victor Co. Ltd., 

Montreal 
John Young, Benograph, Montreal 

G. Graham (Chairman), National Film 
Board, Ottawa 

Editor's Note: This report was kindly 
prepared by Gerry Graham, Director of 
Technical Operations, National Film Board 
of Canada, upon our request for help in 
adding to the series of brief articles de- 
scribing organizations which SMPTE 
members wish to know more about. 
Previous stories have been about the 
American Documentation Institute, the 
Biological Photographic Association, and 
the University Film Producers Association. 
Your suggestions for subjects or possible 
contributors for other articles are welcome. 



157 



New Members 



The following members have been added to the Society's rolls since those last published. 
The designations of grades are the same as those used in the 1952 MEMBERSHIP DIRECTORY. 



Honorary (H) 



Fellow (F) 



Active (M) 



Associate (A) 



Student (S) 



Baggs, Sgt. David A., Officer in Charge of 
Motion Picture Processing, U.S. Air 
Force. Mail: 2413 Girard PL, N.E., 
Washington 18, D.G. (A) 

Barr, William J., Camera Technician, 
Warner Bros. Mail: 5537 Costello 
Ave., Van Nuys, Calif. (A) 

Benedict, Joel A., Director, Bureau of 
Audio-Visual Aids, Arizona State Col- 
lege. Mail: 929 McAllister, Tempe, 
Ariz. (M) 

Beyer, Walter, Motion Picture Engineer, 
Bell & Howell Co. Mail: 7455 N. 
Greenview Ave., Chicago 26, 111. (A) 

Board, Cornelius Z., Arizona State Col- 
lege. Mail: Route 1, Scottsdale, Ariz. 
(S) 

Bonner, Ray S., Recording Engineer, 
Gallagher Films, Inc. Mail: 5062 N. 
54 St., Milwaukee, Wis. (A) 

Cackowski, John, University of California. 
Mail: 5324 Monroe St., Los Angeles 
38, Calif. (S) 

Chaffee, William H., President. Model 
Builders, Inc., 5300 W. 63 St., Chicago 
38, 111. (.M) 

Clark, Dick H., Student and Teaching 
Assistant, University of California, Mo- 
tion Picture Dept., 405 Hilgard, Los 
Angeles, Calif. (A) 

Cooper, Richard J. G., Technical Officer, 
Dept. of National Defense, No. 11 Supply 
Depot, R.C.A.F., Calgary, * Alberta, 
Canada. (A) 

Copeman, Robert A., Motion Picture 
Service Engineer, Box 2140, Salisbury, 
Southern Rhodesia. (A) 

Curran, Charles W., Motion Picture Pro- 
ducer, Times Square Productions, Inc. 
Mail: 145 W. 45 St., New York 36, 
N.Y. (M) 

Damm, Roger, American Television Insti- 
tute. Mail: 7408 Warren Ave., Forest 
Park, 111. (S) 

Donovan, Lewis N., Chief Radio Oper- 
ator, Alberta Government, Dept. of 
Lands & Forests. Mail: 10028105 
St., Edmonton, Alberta, Canada. (A) 

Dunn, Reginald S., Laboratory Tech- 
nician, Color Reproduction Co. Mail: 
4841 Stansbury Ave., Sherman Oaks, 
Calif. (A) 

Edwards, Marvin J., Arizona State Col- 
lege. Mail: 6225 N. 47 Ave., Glen- 
dale, Ariz. (S) 



Fernandez, Victor M., National Airlines, 

Inc. Mail: 13 y Ave. Primera, Ampl. 

de Almendares, Havana, Cuba. (A) 
Gerard, Morton T., Jr., Motion Picture 

Photographer, North American Avia- 
tion, Inc. Mail: 2457 Ashland Ave., 

Santa Monica, Calif. (A) 
Gilkeson, David C., Project Engineer 

(Optics), Wollensak Optical Co., 850 

Hudson Ave., Rochester 21, N.Y. (M) 
Hall, Carlisle D., Laboratory Manager, 

Ansco. Mail: 5506 N. Winthrop Ave., 

Chicago 40, 111. (M) 
Herzig, Leonard A., President, Sound 

Engineer, Prestoseal Manufacturing 

Corp. Mail: 87-11 35 Ave., Jackson 

Heights, N.Y. (M) 
Hine, Sheldon, Technical and Engineering 

Photography, 2538 Joan St., Fort 

Wayne, Ind. (A) 
Holblinger, Anton, Sound Engineer, 

Photo-Magnetic Sound Studio, Inc. 

Mail: 35 Princeton St., Valley Stream, 

L.I., N.Y. (M) 
Jennings, Forrest, Laboratory Technician, 

Color Reproduction Co. Mail: 2363 

Hermits Glen, Hollywood 46, Calif. 

(A) 

Johnson, Culver, Engineer, Culver John- 
son Research, 871 Seventh Ave., New 

York, N.Y. (M) 
Jones, Almon, U.S. Naval Photographic 

Center. Mail: 3130 Knox St., S.E., 

Washington, D.C. (A) 
Klein, Gerard, New York University. 

Mail: 205 Beach 81 St., Rockaway 

Beach, N.Y. (S) 
Marcus, Wil, Motion Picture Producer, 

Loucks & Norling Studios, 245 W. 55 St., 

New York 19, N.Y. (M) 
Meunier, Jean L., President, Institut 

Teccart, Inc., 3155 Hochelaga St., 

Montreal 4, Canada. (A) 
Mikrut, Stanley M., Motion Picture Lab- 
oratory Technician, Coronet Films. 

Mail: 2460 Winona St., Chicago 25, 

111. (A) 
Minis, Charles W., Mechanical Engineer, j 

Technicolor Motion Picture Corp. 

Mail: 124^ N. Parkview St., Los! 

Angeles 26, Calif. (A) 
Reiche, Ludwig P., Electrical Engineer, j 

International Telemeter Corp. Mail: 

1445 Miller Way, Hollywood 46, Calif. 

(M) 



158 



Rocha, Gustavo Humberto E., Head, tion, RCA Broadcast Section. Mail: 

Sound Service and Installation Dept., 222 W. Plumstead Ave., Lansdowne, Pa. 

Casa Ehlers. Mail: Abraham Gon- (M) 

zalez #4, Mexico- City, Mexico. (A) Vaughan, Leslie D., Photographer, State 

Scherlis, William, Cameraman, 241 U. S. Geological Survey, 404 Natural Re- 
Grant Hotel, San Diego 15, Calif. (A) sources Bldg., Urbana, 111. (A) 

Schulman, Marvin, Television Engineer, Wallace, Charles A., Arizona State Col- 

KPIX, Inc. Mail: 175 Buckingham lege. Mail: 600 E. Second, Roswell, 

Way, Apt. 1A, San Francisco 27, Calif. N.M. (S) 

(A) Winkler, Ben, Sound Mixer, Radio 

Simpson, Richard L., Motion Picture Corporation of America. Mail: 11209 

Projection Equipment Mechanic, Naval Emlita St., North Hollywood, Calif. 

Photographic Center. Mail: 3716 (A) 

Second St., S.E., Washington 20, D.C. Wolfe, Benjamin, Television Broadcast 

(A) Engineer, WAAM-TV. Mail: 3513 

Steel, Lt. Col. W. Arthur, Radio Engineer, Lucille Ave., Baltimore 15, Md. (A) 
Federal Electric Manufacturing Co. Worley, E. Max, Motion Picture Tech- 
Mail: 4737 Grosvenor Ave., Montreal, nician, Color Reproduction Co. Mail: 
P.Q., Canada. (M) 10552 Putney Rd., Los Angeles 64, Calif. 

Theiss, Sylvester E., Technical Writer (A) 
(Electronics), U.S. Government. Mail: 

310 Audrey La., S.E., Washington 20, CHANGES IN GRADE 

D.C. (M) Miller, William J., (A) to (M) 

Tunnell, George W., Product Administra- Roberts, Paul M., (S) to (A) 

SMPTE Lapel Pins 

The Society will have available for mailing after September 15, 1952, its gold and blue 
enamel lapel pin, with a screw back. The pin is a -in. reproduction of the Society 

symbol the film, sprocket and television tube which appears on the Journal cover. 

The price of the pin is $4.00, including Federal Tax; in New York City, add 3% 
sales tax. 



Meetings 



72d Semiannual Convention of the SMPTE, Oct. 6-10, Hotel Statler, 

Washington, D. C. 

Other Societies 

International Society of Photogrammetry, Conference, Sept. 4-13, Hotel Shoreham, 

Washington, D.C. 

American Standards Association, Third National Standardization Conference, Sept. 

8-10, Museum of Science and Industry, Chicago, 111. 

Illuminating Engineering Society, National Technical Conference, Sept. 8-12, Edge- 
water Beach Hotel, Chicago, 111. 

Biological Photographic Association, Annual Meeting, Sept. 10-12, Hotel New Yorker, 

New York 

National Electronics Conference, Annual Meeting, Sept. 29-Oct. 1, Sherman Hotel, 

Chicago, 111. 

Optical Society of America, Oct. 9-11, Hotel Statler, Boston, Mass. 

American Institute of Electrical Engineers, Fall General Meeting, Oct. 13-17, New 

Orleans, La. 
American Standards Association, Annual Meeting, Nov. 19, Waldorf-Astoria, New York 



SMPTE Officers and Committees: The roster of Society Officers and the 
Committee Chairmen and Members were published in the April Journal. 



159 



New Products 



Further information about these items can be obtained direct from the addresses given. 
As in the case of technical papers, the Society is not responsible for manufacturers' state- 
ments, and publication of these items does not constitute endorsement of the products. 





This 5000-w Featherlite, weighing only 
21 Ib, is among the spotlights and other 
new studio lighting equipment described 
in a brochure by Century Lighting, Inc., 
521 W. 43d St., New York 36, N.Y. 
Other equipment is: aluminum barn 
doors, mechanical dimmers, light lifts, 
hangers and mike boom. 



The Hy-Arc is a new carbon-arc pro- 
jection lamp for indoor and medium-size 
drive-in theaters that has been announced 
by the Theatre Equipment Section, RCA 
Victor Division of Radio Corporation of 
America, Camden, NJ. Features of the 
lamp are : a system of magnetic stabiliza- 



tion of the arc flame; water-cooled, non- 
rotating positive carbon; and a 15-in. 
high-speed reflector. The lamp's output 
is approximately 18,000 1m. It operates 
with a 9-mm X 20-in. high-intensity 
positive carbon and a ^-in. X 9-in. 
negative carbon at currents from 70 to 
90 amp. 



160 



SMPTE Engineering Activities 



A report by F. T. BOWDITCH, Engineering Vice-President 



_L HE ENGINEERING ACTIVITIES of the 

Society of Motion Picture and Tele- 
vision Engineers are much more ex- 
tensive than perhaps most members 
realize. Engineering Committee reports 
appear in the Journal from time to time, 
but usually these give a detailed picture 
in a rather limited field rather than a 
broad view of the total activity. The 
frequent publication of proposed Ameri- 
can Standards is another evidence of 
Society engineering activity, but this 
has sometimes created the feeling that 
the preparation of Standards proposals 
is the only activity in which the Engi- 
neering Committees of the Society are 
engaged. For these reasons, the writer 
has been encouraged to prepare this 
present report, designed to provide an 
overall picture which, while perhaps 
over-simplified in the particular details 
most familiar to any one reader, will 
at the same time give him information 
of general interest in other less familiar 
fields. 



Editor's Note: This report, scheduled for 
some time for the Journal, now has special 
significance as a summing up by Engineer- 
ing Vice-President Bowditch who, because 
of new responsibilities at the Research 
Laboratories, National Carbon Company, 
Cleveland, Ohio has found it necessary to 
resign before the expiration of his present 
term. He has served the Society as its 
Engineering Vice-President since January 
1950. 



Foremost in the engineering activities 
of the Society is of course the work of its 
Engineering Committees. From 1 to 75 
pages of any individual Journal issue may 
be devoted to this field, and a check of 
Journals since January, 1950, shows an 
average of about 17 such pages per 
issue. This includes not only Com- 
mittee Reports and the publication of 
proposed and final American Standards, 
but records of Convention symposia 
growing out of Committee deliberations 
on such widely different and often 
highly controversial subjects as pre- 
ferred screen-viewing conditions, pro- 
posed magnetic film standards and 
16mm emulsion position. A complete 
bibliography of Engineering Committee 
publications would thus be very exten- 
sive indeed, and much too long for in- 
clusion here. For this reason, the ref- 
erences cited are confined to publica- 
tions during the writer's term of office 
except for a few much earlier ones of 
historical interest. 

The Society prides itself on providing 
in these Committees a completely 
neutral atmosphere, without com- 
mercial bias, where the most active 
competitors can get together to work out 
their common problems. A more com- 
plete statement of the high regard in 
which the Society holds its responsi- 
bilities here will be found in the policy 
statement 1 published by the writer 
soon after assuming the Engineering 



September 1952 Journal of the SMPTE Vol. 59 



161 



Vice-Presidency in January, 1950. It 
will be noted from this that while the 
Engineering Committees do determine 
appropriate test methods, and sometimes 
set limits characteristic of good per- 
formance, the Society is never permitted 
to become involved in the application 
of these to the comparative rating of 
competitive merchandise. 

As has been implied, a major activity 
of the Engineering Committees is the 
determination of proposals to be recom- 
mended as American Standards. An 
American Standard can only be vali- 
dated by the American Standards 
Association, according to a procedure 
which will be described later; but a 
great deal of spadework is required to 
reconcile competitive viewpoints and 
to phrase a proposal combining the 
resultant area of agreement with the 
technical accuracy necessary to a useful 
standard. In motion picture and re- 
lated television fields, the spadework 
for a particular standard is done by one 
of the Engineering Committees of the 
SMPTE. This arrangement is a rela- 
tively recent one, and much simpler 
than before, as will be explained later. 
Also, since SMPTE as sponsor of ASA 
Sectional Committee PH22 is responsible 
for the general organization and work 
program of this Committee, the Engi- 
neering Vice-President is able to co- 
operate effectively within the ASA 
toward this same goal of a simplified 
Committee organization of maximum 
efficiency. 

Particularly with the expansion of the 
Society's interests into related fields of 
television, possibilities for conflict de- 
veloped between the agenda of SMPTE 
Engineering Committees and those of 
other technical societies. This soon 
led to the formation of a steering com- 
mittee, which now bears the impressive 
title "Joint Committee for Inter-Society 
Coordination," and is composed of two 
delegates each from IRE, RTMA, 
SMPTE and most recently NARTB. 
The several committees of SMPTE in 



television fields have been set up with 
the knowledge and guidance of this 
group, and their agenda coordinated 
with those of potentially conflicting 
Committees of the other Societies repre- 
sented. Here too an unnecessary burden 
was formerly placed upon many indus- 
tries asked to contribute the time and 
expenses of technical employees to the 
Committees of several societies simul- 
taneously engaged in solving what 
seem to be the same problems. It is 
the purpose of the JCIC Committee to 
eliminate such waste, at least among the 
member Societies. The Chairmanship 
of this group rotates among the eight 
members on an annual basis, each 
Society being represented in turn. Mr. 
Axel Jensen started things off last year 
as the IRE representative, while the 
writer is serving for SMPTE during 
1952. 

In the following paragraphs the origin 
and the work of each of the Society's 
Engineering Committees will be de- 
scribed in turn. From this it will be 
apparent that much besides American 
Standards proposals occupies these 
groups, and it is hoped that some useful 
measure of the important services ren- 
dered to the Society and to industry will 
be brought out. 

Color 

This Committee has been con- 
tinuously active since its creation in 
1929, and is thus one of the oldest com- 
mittees of the Society. Dr. Herman 
H. Duerr of Ansco has just concluded 
two very capable terms as chairman, and 
has now been succeeded in this post 
by Dr. J. P. Weiss of Du Pont. The 
sixteen members of the Committee are 
chosen to represent the film and equip- 
ment manufacturers, as well as the 
studio users of color film. Although no 
American Standards have been needed 
recently in this field, the Committee 
has been actively concerned with such 
matters as a color process symposium, 
color sensitometry, color film sound 



162 



September 1952 Journal of the SMPTE Vol. 59 



tracks, spectral requirements of light 
sources and projection screens and light- 
source color measuring instruments as 
applied to photography. A subcom- 
mittee under Lloyd Goldsmith prepared 
a very complete table on "Characteris- 
tics of Color Film Sound Tracks," 2 and 
another subcommittee under Carl Over- 
hage published an excellent 72-page 
treatise on "Principles of Color Sensitom- 
etry." 3 These two examples illustrate 
very well the important work in fields 
other than standardization which is 
being done by the Engineering Com- 
mittees of the Society. 

Curiously enough, the one proposal 
for standardization which this Com- 
mittee has received in recent years was 
necessarily postponed until the trade 
situation is further clarified. It was 
pointed out to the Committee that 
several sorts of color film are presently 
on the market, each balanced for 
photography with an incandescent tungs- 
ten light source of a different color 
temperature. Standardization on a 
single color temperature would obviously 
provide for simpler stocking of film 
and of light sources, and so would seem 
a proper subject for consideration by the 
Committee; moreover, if the lower color 
temperature could be made standard, 
lamp life would be much prolonged. 
It was soon agreed, however, that 
standardization was not appropriate at 
this time because many economic factors 
remain to be clarified before the best 
balance between picture quality, film 
speed and light color and intensity can 
be determined. The Society has no 
right, nor in fact does it have the power, 
to force a single standard where sub- 
stantial unanimity cannot be secured; 
nor are the facilities available to con- 
duct extensive technical studies under 
Society auspices, and so assume the re- 
sponsibility for securing the one best 
answer to a complicated problem such 
as this one. 

C. Francis Jenkins, first president of 
this Society, gives excellent precedent 



for this present-day action in an address 
on "Society History" 4 delivered in 1918. 
Reporting an unsuccessful attempt "to 
adopt an alleged ideal specification for 
a projection machine" on account of the 
objections "by makers of diverse models," 
he concluded as follows: 

"It did one thing, however, well 
worth while. It clarified the atmos- 
phere and made more distinct to. me 
and perhaps to others of us, the objects 
for which this Society was organized 
and even more strikingly the things for 
which it is not organized. 

"For example, the Society of Motion 
Picture Engineers is not a judicial body 
to settle controversies between con- 
flicting interests or to promulgate recom- 
mendations which make for class-dis- 
crimination. If our Society ever de- 
generates into a contest between factions 
each trying to use the Society for per- 
sonal advantage, then our usefulness is 
ended and our organization will soon 
break up as others in the motion picture 
industry have already done. 

"What we did organize for was to 
set our official seal on standards generally 
recognized as standards; and second, 
and perhaps best of all, to put into 
permanent form for world-wide dis- 
tribution, the specialized knowledge 
which our members, experts in their 
particular line, are so unselfishly furnish- 
ing for this purpose. And while the 
official stamping of generally acknowl- 
edged standards is a necessary duty, 
for myself I have found the most interest 
in our meetings has come from the 
valuable papers read and printed, and 
I don't believe the limited time of our 
meetings can be spent in a more worth- 
while manner." 

Film Dimensions 

This is a relatively new Engineering 
Committee, established in 1948 by the 
preceding Engineering Vice-President, 
John A. Maurer. The Society has been 
active in the field of film dimensions 
from the very beginning, however, as 



F. T. Bow ditch: Engineering Activities 



163 



witness the presentation by Donald J. 
Bell of a paper on "Motion Picture Film 
Perforation" at the meeting of October 
2-3 in 1916, the second formal meeting 
of the Society. Bell's demand for 
standardization started a continuing 
activity, through first a "Committee on 
Cameras and Perforations" in 1916, then 
a "Committee on Film Perforations" in 
1921, which continued as a subcommittee 
of the Committee on Standards from 
1924 to 1948. In line with the philos- 
ophy of simplification previously ex- 
pressed, the long-standing importance 
of film dimensions was once more 
recognized, and the former subcom- 
mittee was made a full-fledged Engineer- 
ing Committee in 1948. Dr. Emmett 
Carver of Eastman Kodak has been 
the very competent Chairman of this 
group since its formation, the members 
representing the film manufacturing 
companies and those most concerned 
with the handling of film through appa- 
ratus in which dimensional tolerances 
are critical. 

The biggest problems facing this 
Committee at present are those relating 
to the introduction of the new safety- 
type film bases. Film is ordinarily slit 
to dimension and perforated at the time 
of manufacture. After an indeterminate 
period of time, involving perhaps pro- 
longed storage under various humidities 
and temperatures, and chemical proc- 
essing, this film must pass smoothly 
and with great accuracy of positioning 
through a camera, printer, projector or 
perhaps some other sort of specialized 
film-handling equipment. The critical 
dimensions of these equipments have 
been chosen by long experience to 
match the characteristics of the old-style 
film base. Now, with new bases with 
different dimensional changes being 
introduced, the shoe is on the other 
foot: the film manufacturer must alter 
his initial slitting and perforating dimen- 
sions so that the dimensions in critical 
usage will be the same as before. Ameri- 
can Standards for film dimensions pres- 



ently "apply to the material imme- 
diately after cutting and perforating": 
the later dimensions at the time of film 
passage through an apparatus of some 
sort are of course known to be most 
important, but to date no one has been 
able to visualize a suitable procedure 
for extrapolating these back to the time 
at which the slitting and perforating is 
done. 

Another problem of this Committee 
has been concerned with the possible 
choice of a single preferred shape for 
the sprocket perforation of 35mm positive 
and negative film. A proposal for this 5 
has been forwarded to the Committee 
on Standards with the recommendation 
that it be made an American Standard. 

Finally, a recent policy decision in 
the field of film dimensioning is worthy 
of notice. Not all film is slit at the time 
of manufacture. 16mm and 8mm film 
stock is sometimes provided double- 
width, to facilitate processing, with final 
slitting-to-width done after processing. 
For one reason or another, a good deal 
of the film made in this way has not been 
slit with the accuracy in width required 
to meet the American Standard di- 
mensional tolerances, and poor sound 
reproduction, excessive picture weave 
and even film jamming in projection 
has resulted. The Committee con- 
sidered the desirability of preparing a 
second and less rigid dimensional stand- 
ard for 16mm film, to apply only to film 
slit from 35mm or 32mm stock after 
processing. This idea was soon re- 
jected, however, on the basis that the 
present 16mm dimensional specification 
is required for interchangeable per- 
formance in all equipments, without 
reference to the manner in which the 
film is made. Thus there is no logical 
reason to let down the bars solely for 
the purpose of permitting all laboratory- 
slit product to qualify under a Standard 
of some sort. Since American Standards 
are not compulsory, a considerable 
market can and often is developed in 
nonstandard merchandise of all sorts. 



164 



September 1952 Journal of the SMPTE Vol. 59 



It was concluded, however, that the 
demonstration of the existence of such a 
market is no reason to dignify it with a 
high-quality label. 

Film Projection Practice 

No matter what talent and expense 
have gone into the preparation of a 
fine motion picture film, the film must 
finally be projected with proper skill 
and good equipment in order to yield 
the proper end product. Projectionists 
and equipment manufacturers alike 
have always recognized this critical 
importance of high-quality projection, 
ever since this Committee was first 
established under the chairmanship of 
F. E. Richardson in 1928. Many will 
recall the fervent pleas for good pro- 
jection practice which were a valued 
contribution of Mr. Richardson to the 
Convention sessions of more than a 
quarter century ago. He was perhaps 
more responsible than any other person 
for halting the early practice of referring 
to the men in the booth as simply 
"operators," and seeing to it that the 
more appropriate term "projectionist" 
came into common usage. 6 The torch 
is presently being carried by Ralph 
Heacock of RCA, who has recently 
succeeded M. D. O'Brien of Loew's 
in this important Chairmanship. A few 
years ago the word "Film" was added 
to the name of this Committee, in 
recognition of the advent of television 
projection in theaters, and the assign- 
ment of this latter aspect to the Com- 
mittee on Theater Television. 

The membership of the Committee 
on Film Projection Practice is presently 
composed largely of projection equip- 
ment manufacturers and theater circuit 
representatives, although we would like 
to add more projectionists to this group. 
An interesting agenda includes revision 
of the projection room plans, the possible 
preparation of projection room main- 
tenance instructions, preparation of a 
proposed standard for arc-lamp mount- 



ing dimensions and the review of three 
American Standards dealing with pro- 
jector aperture dimensions, basic pro- 
jection room and lens dimensions and 
35mm projection reels. 

Films for Television 

This Committee was first formed early 
in 1950, in line with the expanding 
interests of the Society in television fields. 
Previous to 1950, only two SMPTE 
television committees were in existence 
one on Theater Television and one on 
simply Television. The latter became 
unwieldy as interests broadened, and 
so was divided into three Committees, 
on Films for Television, Television Film 
Equipment and Television Studio Light- 
ing, respectively. 

The Committee on Films for Tele- 
vision is chaired by Dr. R. L. Garman 
of General Precision Laboratory, and 
is staffed by film, equipment and 
television studio representatives. The 
committee is concerned with the special 
problems of film as used in television, 
and has been especially active in the 
field of "Television Test Films" 7 which 
has presented some very difficult prob- 
lems, and in the preparation of a "New 
All-Pur pose Film Leader" 8 by a very 
capable and energetic subcommittee 
led by C. L. Townsend of NBC. Other 
projects include a study of the problems 
concerned with pictorial quality of films 
for television use, and a study along with 
other Committees of the long-standing 
problem of 16mm emulsion position. 9 
The reference noted should be consulted 
by those interested in this problem. 
The television picture and sound prob- 
lems arising from the indiscriminate use 
of film for projection with emulsion 
sometimes facing the light source and 
sometimes the lens, was thoroughly dis- 
cussed during the October 1951 Con- 
vention in Hollywood. 10 It was agreed 
then that it is up to the purchaser to 
specify and pay for the emulsion position 
he wants, and some television studios 



F. T, Bow ditch: Engineering Activities 



165 



report very good success in this way. 
The Hollywood symposium on 16mm 
emulsion position is worthy of special 
mention here as a typical example of 
an engineering service growing out of 
Engineering Committee activity. 



High-Speed Photography 

This Committee was first organized 
by Engineering Vice-President John A. 
Maurer in 1 948, with John H. Waddell 
as Chairman and with a membership 
representing film and equipment manu- 
facturers along with an excellent repre- 
sentation of the users of this very special- 
ized equipment. Under Waddell, this 
group got off to a most energetic start, 
although more along the lines of a 
Papers Committee in its field, rather 
than with an agenda of engineering 
problems to be solved as is the case 
with the other Engineering Committees. 
In the papers field, the Committee on 
High-Speed Photography has sponsored 
technical sessions for one or more days 
at several Conventions and has published 
"A Survey of High-Speed Motion 
Picture Photography" and a "Bibliog- 
raphy on High-Speed Photography," 11 
while sponsoring the "High-Speed Pho- 
tography Question Box." 12 A "Sub- 
committee on Technical and Engineer- 
ing Society Liaison" was organized last 
year with representatives from about 
twelve other technical organizations, 
although it is too early to judge what 
may come from this attempt to correlate 
all technical-society effort in this field. 

When John WaddelPs permissible 
limit of two terms (four years) as Chair- 
man terminated last January, we were 
fortunate in securing the services of Dr. 
Harold E. Edgerton of M.I.T. in this 
post. With the planning of an Inter- 
national Symposium on High-Speed 
Photography for the Washington meeting 
next October, the Committee is con- 
tinuing its typically fast pace along this 
line. 



Laboratory Practice 

This is another of the Society's long- 
standing Committees, organized first as 
a committee on Laboratories in 1921, 
then Development and Care of Films in 
1931, Laboratory and Exchange Prac- 
tice in 1933, and finally as a separate 
Committee on Laboratory Practice since 
1935. This Committee has never oper- 
ated with more energy and effective- 
ness than during the last few years 
under the Chairmanship of John Stott 
of Du-Art Film Laboratories. Member- 
ship is recruited largely from the proc- 
essing laboratories, as the title would 
suggest. 

Projects of this group include the 
determination of a standard screen 
brightness for 16mm review rooms, so 
that the customer and the laboratory 
may judge the product on an agreed 
common basis. Difficulties presently 
arise here on account of the conflicting 
demands of the Armed Services for thin 
prints to be projected at low light levels, 
and the need for dense prints for the 
amateur's small, beaded screens and 
1000-watt projection lamps. 

The standardization of printer cueing 
devices is another project of much po- 
tential value. Negatives circulate widely 
between laboratories and since there is 
no present agreement respecting these 
cueing devices, much patching and 
mutilation of the film results. 

Emulsion position with 16mm posi- 
tive films has also been discussed long 
and often by this group. Here too it is 
concluded that no single standard will 
ever be observed until the customers 
apply the necessary pressure and agree 
to pay the extra cost where this is in- 
volved. Standard magnification ratios 
when printing between 35mm and 
16mm film sizes, and assistance to the 
Armed Services in setting up better 
specifications for print quality are other 
problems. The recent establishment 
of a Chemical Corner 13 in the Journal is 



166 



September 1952 Journal of the SMPTE Vol. 59 



another important service provided by 
this Committee. 

Motion Picture Studio Lighting 
and Process Photography 

A Society committee on Studios was 
first organized in 1917, followed by one 
on Studio Lighting in 1928, which has 
operated continuously since that time. 
The term "Motion Picture" was added 
to the Committee title in 1950 to dis- 
tinguish this from the newly created 
Television Studio Lighting Committee. 
A former Committee on Process Photog- 
raphy was combined with the Studio 
Lighting Committee in 1951, following 
a six-year period of carrying the former 
on the books as "under organization," 
with little evidence that such organiza- 
tion was really needed. 

This illustrates another basic principle 
of Engineering Committee operation. 
These Committees come and go and 
perhaps return again as the needs 
of the industry require. There is never 
any intention to carry a Committee 
simply as a listing of names in the 
Journal, and such a listing is terminated 
as soon as reasonable efforts to stimulate 
activity prove unsuccessful. Activity 
solely for activity's sake is never en- 
couraged; but if there is useful work to 
be done, every effort is made to enlist 
competent persons to do it. 

M. A. Hankins of Mole-Richardson 
has recently concluded a very competent 
two-term maximum as Chairman of the 
Committee on Motion Picture Studio 
Lighting and Process Photography, and 
he is now succeeded in this post by 
John W. Boyle, Director of Photog- 
raphy. This group is based in Holly- 
wood, and is composed of studio lighting 
equipment representatives and persons 
who are concerned with set lighting. 
Since the proper use of lighting is largely 
a matter of art, the field of the engineer 
is limited here. In spite of this, the 
Committee regularly prepares compre- 
hensive reports 14 which are most useful 
in acquainting the industry with the 



latest things in set illumination equip- 
ment and their studio usage. 

Another motion picture studio group, 
the Committee on Cinematography, 
also based in Hollywood, was temporarily 
inactivated a year ago, after no interest 
had been manifest for a considerable 
number of years. 

Limited West Coast activity in Society 
Engineering Committee work is no doubt 
in part the result of basing the Engineer- 
ing direction almost 3000 miles away, 
in the New York headquarters of the 
Society. Another factor, of course, is 
the fine work of the Motion Picture Re- 
search Council and * of the American 
Society of Cinematographers in related 
fields. The Society enjoys the best 
possible cooperation with these organi- 
zations, and of course has no interest 
in attempting to duplicate their work. 
Nevertheless, the Engineering Vice- 
President has repeatedly felt a sense of 
responsibility to encourage more activity 
in the West Coast committees which are 
part of the traditional engineering 
organization of the Society. Any sug- 
gestions here will be most welcome. 

Optics 

Reference to the first volume of the 
Transactions of our Society indicates a 
very early interest in the subject of 
optics, a Committee on Optics having 
been formed in October 1916 and re- 
maining active through 1923. From 
1930 through 1934 a Committee on 
Projection Theory was concerned with 
this field, but this was absorbed by the 
Committee on Standards in 1935. 
Finally, a subcommittee of the Com- 
mittee on Standards was once again 
given full committee status in 1950 with 
the establishment of the present Com- 
mittee on Optics. Dr. R. Kingslake 
of Eastman Kodak has served as Chair- 
man since that date. 

The first major assignment of this 
Committee has been the preparation of 
a proposed standard for the photometric 
calibration of camera lenses. The group 



F. T. Bowditch: Engineering Activities 



167 



has agreed on two methods, either of 
which gives accurate results. A recom- 
mendation has also been submitted 
respecting the standardization of an 
associated lens marking system in so- 
called "T-stops," but this portion of the 
proposal is finding considerable opposi- 
tion from those who feel that the valida- 
tion of a T-stop lens marking method 
will lead amateurs to expect a greater 
exposure accuracy than will likely result. 
The Committee has done a very excel- 
lent technical job in specifying accurate 
calibration methods, a procedure which 
has been much facilitated by the 
generosity of the Radio Corporation of 
America in granting licenses under a 
patent issued to L. T. Sachtleben of 
RCA. If the T-stop versus /-stop 
controversy proves insoluble, it is hoped 
that the test methods can in some way 
be made standard, independent of the 
provocative term "T-stop." 

Other projects of this group include 
the specification of lens mounting dimen- 
sions for 35mm, 16mm and 8mm film 
projectors, and standard lens resolution 
test procedures. 

Screen Brightness 

The present Screen Brightness Com- 
mittee dates back to the Committee 
on Theater Engineering of 1941. This 
latter Committee consisted at that time 
of a combination of several subcom- 
mittees, including one on Screen Bright- 
ness. This subordinate status con- 
tinued through 1945, after which the 
several subcommittees of the Theater 
Engineering Committee were each given 
full Engineering Committee status. Dr. 
W. W. Lozier of The National Carbon 
Company is the present Chairman of 
this very active group. 

A major activity here has been the 
screen brightness survey, 15 which has 
now been extended to cover 125 indoor 
theaters and 1 8 West Coast 35mm review 
rooms. Much helpful information has 
been secured, and this is being extended 
to include a representative number of 



drive-in theaters. An important aspect 
of this work has been the specification of 
a suitable light-measuring equipment 
and method of use. 

A symposium on screen viewing fac- 
tors 16 was sponsored by this Committee, 
providing not only a most instructive 
Convention session but also more than 
50 pages of technical papers in the 
Journal. The great importance of these 
screen viewing factors is fully recognized 
by the Committee, which is presently 
working to stimulate commercial in- 
terest in the psychological test pro- 
cedures required to get the audience 
reaction data needed. 

A basic problem in standardization 
recently developed when a question 
arose respecting the omission of drive-in 
theaters from the American Standard 
specification of screen brightness (101J 
ft-L). No commercial projection equip- 
ment can presently supply, nor will 
present film withstand, the quantity of 
light required to illuminate large drive-in 
screens to this level. So, no matter 
how good his intentions, the owner of a 
drive-in can only meet the present 
American Standard by cutting the size 
of the screen and the capacity for 
customers to an impractical extent. 
Rather than give a "nonstandard" label 
to all the drive-in theaters in the coun- 
try, the Committee therefore voted to 
omit them altogether from the speci- 
fication. This is in line with the basic 
principle that an American Standard 
should be a commonly accepted practice, 
capable of realization in a commercial 
way, and not simply a theoretical 
quality goal for the indefinite future. 

The Screen Brightness Committee 
now has active Subcommittees on: 
Meters and Methods of Measurement, 
Projection Screens, and Illumination 
Practices. 

16mm and 8mm Motion Pictures 

This group was first organized as the 
Committee on Nontheatrical Equipment 
in 1931, assuming its present title in 



168 



September 1952 Journal of the SMPTE Vol. 59 



1946, in recognition of the growth of 
16mm usage to include important 
theatrical as well as many other signifi- 
cant high-quality applications. Be- 
cause there is much less film area than 
with 35mm film on which to record 
picture and sound information, the 
16mm engineers are encouraged to seek 
the best possible quality in all their 
operations. Learning in this way what 
careful attention to quality can produce, 
these engineers have made of this Com- 
mittee a very active forum for the ex- 
change of ideas and information, and an 
effective influence for higher quality 
in all phases of the industry. 

This interest in all phases calls atten- 
tion to the fact that this Committee is 
the only one set up along product rather 
than along process lines, so that oppor- 
tunities for conflict with the work of 
the other committees frequently arise. 
For instance, problems in 16mm film 
dimensions, laboratory practice, sound, 
etc., might equally well be handled by 
the committees in these particular fields. 
This situation has developed from the 
early days when 16mm was regarded as 
"substandard," and no one even thought 
of 8mm film. 35mm sound engineers, 
as an example, had no interest in 
16mm, so that two entirely different 
groups of people were required to 
represent those interested in the 35mm 
and 16mm applications respectively. 
Now that this is no longer true, tradition 
and a very active record of accomplish- 
ment have operated to maintain a com- 
mittee which would probably not be 
reorganized at all if we were to ruthlessly 
start over again in the light of the present- 
day committee arrangement. However, 
no Society would be foolish enough to 
disband or even to limit the work of a 
group as active and as useful as this one 
continues to be. 

This Committee in recent years has 
done an outstanding job of developing 
American Standards proposals, a total 
of approximately 20 being presently in 
various stages of negotiation through 



final confirmation. Much of this has 
come from intensive work with the 
Armed Services during World War II, 
directed toward the determination of a 
JAN (Joint Army-Navy) specification for 
a 16mm projector. 

In addition to being the most active 
Committee in the development of stand- 
ards proposals, the 16mm and 8mm 
group is working on recommendations 
for 16mm review rooms, especially 
sound reproducing equipment, a test 
film for checking the resolution of 
projector optical systems, and the prepa- 
ration of a booklet on 1 6mm and 8mm 
Projection Practice. 

The Committee has been faced with 
many difficult standardization problems, 
in some of which unanimous trade 
agreement has been impossible to 
achieve. The familiar one of 16mm 
emulsion position is an outstanding 
example; although an American Stand- 
ard does exist here, this is frequently 
ignored and serves mainly to demonstrate 
the futility of a Standard which does not 
have the acceptance of all concerned. 
Another classic case is the specification 
of the guided edge in several standards 
dealing with 16mm film. Projector 
manufacturers were not in agreement 
in their choice of the sound-track versus 
the perforated edge, since good design 
reasons existed for either one. Now, 
however, a reversal of the earlier ma- 
jority opinion is in prospect, on account 
of the prevalence of increasing amounts 
of substandard 1 6mm film, inaccurately 
slit from 32mm or 35mm after proc- 
essing, and so providing a very inac- 
curate reference edge for the positioning 
of the picture and sound-track areas. 

Present-day difficulties in arriving at a 
standard here are reminiscent of Mr. 
Jenkin's experiences with the first 
standardization efforts of the Society, 
which were previously quoted. Stand- 
ards defining a preferred design for 
quality reasons create many debatable 
issues, and these should ordinarily be 
left for independent resolution by each 



F. T. Bowditch: Engineering Activities 



169 



designer, where critical interchange- 
abilities are not involved. Let the 
Society specify standard test methods, 
including test films, so that the customer 
may determine matters of relative 
product quality in a reliable manner; 
but let us avoid labeling any particular 
product as substandard except where 
critical interchangeability is involved, 
or complete unanimity achieved. 

A final example of this kind is the 
effort made in 1948 to revise an earlier 
American Standard for 16mm sprocket 
design, including features intended to 
insure better quality rather than simply 
interchangeability. Sprockets of a de- 
sign different from that of the proposed 
standard were stated by a major manu- 
facturer to be in wide successful use, and 
his engineers did not agree that the de- 
sign proposed as standard was any 
better than this. Further, to quote E. 
W. Kellogg 17 ". . . if a manufacturer 
puts out a machine which performs well 
with a standard film, and the film is 
not subjected to undue wear, and his 
customers are happy . . . it is no one 
else's business what shape tooth he 
uses." Thus the difficulties first ex- 
perienced by Mr. Jenkins returned to 
trouble us once more. In the sprocket 
case, the Committee on Standards 
adopted a form of recommendation, 
which would permit competent tech- 
nical material of this sort to be published 
in an authoritative manner for the 
general education of the industry, while 
at the same time avoiding the applica- 
tion of a nonstandard label to all other 
designs. This form of publication 18 is 
reserved for standards proposals which 
fail to secure the unanimity necessary 
for standardization, but which do em- 
body much good technical material, 
thought to be of general trade interest. 

Henry Hood of Eastman Kodak has 
just concluded a very capable 4-year 
term as Chairman of the 16mm and 8mm 
Motion Pictures Committee and has 
now been succeeded by Malcolm Towns- 



ley of Bell & Howell. The large 
membership of 23 persons reflects the 
wide range of interests represented. 

Sound 

When talking motion pictures arrived 
with startling suddenness in the late 
1920's, they brought many technical 
problems, and with them, the creation 
in 1930 of the SMPE Committee on 
Sound. This is presently the largest 
of all the Engineering Committees, 
including 27 persons with the Chairman 
(West Coast) and Vice-Chairman (East 
Coast). Representatives of the 35mm 
studios, the 16mm and 8mm industries, 
and television combine with the sound 
equipment, film and magnetic tape 
suppliers to give a very complete cover- 
age of the field. Lloyd T. Goldsmith 
of Warner Bros, has just completed four 
very competent years as Chairman, and 
he has now been succeeded by John 
Hilliard of Altec-Lansing also of Hol- 
lywood. Glenn Dimmick of RCA con- 
tinues as Vice-Chairman in the East, 
and in his Chairmanship of the very 
important Magnetic Subcommittee. 

Major problems in this group have 
to do with standardization, particularly 
respecting magnetic sound. A very 
important symposium respecting mag- 
netic film standards was sponsored 
during the Hollywood convention last 
October 19 giving opportunity for a very 
frank and open presentation of the 
opposing viewpoints. Here is a case 
where the need for a single standard 
was recognized by all concerned, al- 
though each conflicting system had been 
chosen by its sponsor for reasons thought 
to be valid. The invaluable oppor- 
tunity offered by the Society as an 
impartial meeting ground for active 
competitors is well illustrated here, and 1 
there is every reason to anticipate the 
early determination of the single standard 
needed. 

In addition to active work on many 
standards, the Sound Committee does 



170 



September 1952 Journal of the SMPTE Vol.59 



a great deal of work on test films, being 
presently concerned with the specifica- 
tion of new ones related to magnetic 
sound. 

Standards Committee 

This is the most venerable and honor- 
able of all the Engineering Committees, 
going back to the very early days of the 
Society. Standardization in the first 
years was "Adopted in Committee of 
the Whole Society," as witness the first 
"Motion Picture Standards" published 
in the first volume (1916-1920) of Society 
Transactions. These apparently re- 
sulted from the recommendations of 
one of the four engineering committees 
of that time, in fields of Cameras and 
Perforations, Motion Picture Electrical 
Devices, Projection Machines, and Optics, 
respectively. In 1924, a Committee on 
Nomenclature and Standards was 
formed, this being changed to the present 
title in 1934. 

For many years, standardization pro- 
posals were developed by subcommittees 
of the Standards Committee, by sub- 
committees of ASA Sectional Com- 
mittee PH22 on Motion Pictures and 
by any one of the several Engineering 
Committees of SMPTE. This finally 
led to the realization that the most 
competent people in particular fields 
have already been brought together in 
the respective Engineering Committees 
of SMPTE, so that it is most efficient to 
refer all Standards work projects directly 
to these Committees, rather than to 
appoint members of these same Com- 
mittees as a subcommittee of the Stand- 
ards Committee or of ASA Sectional 
Committee PH22. 21 This procedure was 
first inaugurated by John A. Maurer 
and was further facilitated by his ap- 
pointment of all Engineering Committee 
Chairmen as members of the Standards 
Committee. The balance of the Com- 
mittee serves ex officio, and includes a 
representative of the Motion Picture 
Research Council, the chairman of ASA 
Sectional Committee PH22, the Past 



Engineering Vice-President of SMPTE 
and the Past Chairman of the Standards 
Committee. This insures a most compe- 
tent and experienced group of engineers, 
well qualified to handle the policy-type 
matters which come before it, along with 
the processing of standards proposals. 
While the basic policies which are cited 
as examples throughout this report are 
the responsibility of the Engineering 
Vice-President, these are in general the 
result of discussions with the Standards 
Committee, and the determination of a 
consensus there. 

The dean of the motion picture 
standards business is generally recognized 
to be Dr. Emmett Carver of Eastman 
Kodak, who served as Chairman of 
this Committee for many years. Dr. 
Carver brings a very fine attitude of 
patience, impartiality and technical 
thoroughness to these deliberations, and 
his capabilities are universally respected 
by those who work with him in this 
field. Frank E. Carlson of General 
Electric has just completed a competent 
four-year term as Chairman of the 
Standards Committee, and has now 
been succeeded by Henry Hood of 
Eastman Kodak. Hood's recent ap- 
pointment to fill the remainder of the 
current Engineering Vice-President term 
creates a vacancy here which has not 
been filled at this writing. 

Stereoscopic Motion Pictures 

The April 1952 Journal was the first 
to list this new Committee, formed 
since the first of this year. Started a 
few months ago as a task force to report 
on the extent of trade interest in the 
formation of such a permanent Com- 
mittee, the group found the response 
was immediate and very enthusiastic. 
John A. Norling is the ambitious Chair- 
man of this new Committee, and while 
it is too early to predict the relative 
importance and permanence of this 
group, present indications are certainly 
favorable. Two projects presently under 
way are concerned with stereoscopic 



F. T. Bowditch: Engineering Activities 



171 



nomenclature and with the preparation 
of a bibliography ol this field. 

Joint RTMA-SMPTE Committee 
on Television Film Equipment 

This Committee is an outgrowth of 
negotiations in the Joint Committee on 
Inter-Society Coordination. As pre- 
viously noted, the SMPTE realized late 
in 1949 that television interests in the 
Society had grown too large to be con- 
tained within the Committees on Tele- 
vision and on Theater Television. The 
latter was specific enough, but the 
handling of all other interests in a 
single Committee on Television was no 
longer practical. A few months prior 
to any definite action by SMPTE, the 
RTMA independently realized the need 
for technical committee activity in the 
field of television film-handling equip- 
ment, and so formed a very capable 
Subcommittee of Subcommittee 4 of 
RTMA Committee TR4, bearing the 
designation TR4.4.2. Thus, while 
SMPTE was making up its mind, the 
independently conceived RTMA Sub- 
Subcommittee came into being, squarely 
in one of the fields contemplated by 
SMPTE, and immediately gave evi- 
dence of energetic competence. The 
individual members of the RTMA 
committee might just as appropriately 
have been serving with SMPTE, since 
the same commercial" organizations and 
most often the identical persons are the 
ones most logically chosen whenever a 
competent Engineering Committee is 
formed in a specific field such as this 
one. As an example, seven of the 
twelve -man TR4.4.2 Committee were 
already SMPTE members, including the 
Chairman. Thus it was quite im- 
practical for SMPTE to attempt the 
formation of an altogether different 
Committee to do this same job, even 
though this was obviously in a technical 
field where the Society was most expert. 
Hence the formation of the coordinating 
Committee, and the agreement with 
RTMA that this would henceforth be- 



come a joint committee of the two So- 
cieties. Details remain to be worked 
out, since the formal procedures re- 
specting membership appointment and 
chairman selection are not the same in 
the two sponsor organizations. Here 
too the JCIC will prove helpful. 

Dr. Frank N. Gillette of General 
Precision Laboratories continues as 
Chairman of the Joint Committee, with 
Dr. E. C. Fritts as Vice-Chairman, 
representing SMPTE. To the original 
membership of 12, appointed by RTMA, 
SMPTE added six more, from film and 
film equipment agencies not previously 
represented. A major project of this 
group is the preparation of a 16mm 
projector specification, incorporating the 
special requirements of television usage. 
Other projects include a standards 
proposal for dimensions of slides and 
opaques, and one for picture dimensions 
on 16mm and 35mm motion picture 
film. 

It should be mentioned here that 
among the new Committees originally 
considered by SMPTE in the field of 
television was one on Video Recording, 
listed as "under organization" in the 
April, 1950, listing of Committees of 
the Society. In discussions of this in 
the JCIC, it was agreed that aspects 
of this operation of interest to SMPTE 
would properly come before the Com- 
mittees on Film for Television and 
Television Film Equipment. The 
SMPTE Committee on Video Record- 
ing was thus allowed to disband before 
the organization phase was completed. 
An IRE Subcommittee on Video Sys- 
tems and Components is in potential 
conflict here, but it has been suggested 
through the JCIC that this latter group 
do no work on film handling equipment. 

Television Studio Lighting 

This is another of the new television 
committees resulting from the expansion 
of the old Committee on Television. 
Since this field is not in potential con- 
flict with the technical committee work 



172 



September 1952 Journal of the SMPTE VoL 59 



of the IRE, RTMA and NARTB, this 
has been agreed to be outside the field 
of interest of the JCIG. 

The Society has, however, been 
engaged in a running argument with 
The Illuminating Engineering Society 
respecting duplication of effort here, 
which was resolved for a while by an 
IES agreement to leave this to SMPTE, 
while working in IES with the lighting 
problems associated with television view- 
ing. This agreement has since been 
abandoned, however, so that two sepa- 
rate technical committees of quite 
similar membership presently exist in 
the field of television studio lighting, 
one sponsored by SMPTE and one by 
IES. We have recently explored the 
possibility of reducing this to a single 
Joint Committee of the two Societies, 
as with Television Film Equipment, 
but this has so far been unsuccessful, 
and further efforts have now been 
abandoned. 

It has been accepted as a basic policy 
of the SMPTE Committee that only 
those projects shall be undertaken 
which are of admitted interest to the 
television studio engineers. Equipment 
makers and other suppliers of the 
studios are in the minority on the Com- 
mittee, and serve primarily as sources of 
information. 

Richard Blount of General Electric 
is serving his second term as Chairman 
of this Committee, and is presently 
active in promoting the chosen Com- 
mittee objectives of: (1) defining means 
for the measurement of television studio 
lighting, both incident and reflected; 
(2) terminology; and (3) the possible 
standardization of electrical plugs. 

Test Film Quality 

This Committee was first organized 
in 1944, in order to provide expert 
advice respecting the maintenance of 
proper quality of the Society's test 
films. 

Responsibility for defining the content 
of one of these test films lies ordinarily 



with the Engineering Committee most 
concerned, as does the suggestion of new 
test films as their need becomes ap- 
parent. The Quality Committee, on 
the other hand, sees to it that appro- 
priate controls are devised and main- 
tained to insure that the films made are 
in accordance with these specifications. 
With the full time employment of Fred 
Whitney about one year ago, Society 
headquarters facilities for test film 
quality maintenance have been much 
augmented. 

The present Chairman of this im- 
portant Committee is Fred Pfeiff of 
Altec Service Corp., who is exceptionally 
well acquainted with test film quality 
considerations from the user's standpoint. 
The Committee membership consists of 
persons expert in the processing of high 
quality film, including a representative 
of the Motion Picture Research Council. 

Theater Television 

This Committee was first organized 
in 1944 as a Subcommittee on Tele- 
vision Projection Practice of the Com- 
mittee on Theater Engineering, acquir- 
ing the present title of "Theater Tele- 
vision" in 1948. The group has oper- 
ated to date largely as a policy Com- 
mittee, and for the purpose of assembling 
and distributing technical information 
of interest in this important new field. 
The Society has also appeared before 
the Federal Communications Commis- 
sion, presenting data secured through 
this Committee relating to the nature 
of the facilities thought necessary for a 
theater television distribution system. 22 

Largely as the result of the stimulation 
provided through this Committee, many 
business groups became actively in- 
terested in theater television, and these 
have also appeared with increasing 
enthusiasm before the FCC in support 
of this new medium. Finally, it became 
apparent that the services of the Society 
were no longer needed to plead this 
cause, and the Theater Television Com- 
mittee recommended that the Society 



F. T. Bowditch: Engineering Activities 



173 



make no further appearances before 
the FCC since "the new industry is well 
able to solve its own- commercial problems " 
The statement "Theater Television and 
the FCC," 23 should be consulted for 
further details. 

It is anticipated that this Committee 
will some day be concerned predomi- 
nately with the engineering problems 
arising from the operation of television 
projection equipment in theaters. Con- 
sideration is also being given to under- 
taking a study of color television systems 
as applied to theater use. For the 
moment, things must stand by until 
the oft-postponed FCC hearings are 
out of the way, since these must occupy 
the first interest of many of the Com- 
mittee members. Results of these hear- 
ings will also have an important effect 
on the future field of interest of the 
group. 

Paul J. Larsen was the chairman of 
this Committee during the very im- 
portant formative years from 1945 to 
1 948, and his missionary enthusiasm 
did much to keep the spark alive when 
commercial interest waned. Donald 
E. Hyndman took over in 1948 and 
brought Larsen's early work up to the 
point where trade enthusiasm became 
so great that no further Society par- 
ticipation before FCC was needed. 

George L. Beers of RCA is the present 
Chairman, and in talking his assignment 
over with the Engineering Vice-Presi- 
dent and with Mr. Hyndman (who was 
forced to resign on account of the pres- 
sure of other affairs) the following 
general field of operation was agreed 
upon: 

"In general the Theater Television 
Committee should concern itself with 
the study of the engineering factors 
involved in the production of theater 
television programs. Rather than at- 
tempt to prescribe the minimum picture 
quality which a theater television screen 
image must provide in order to be a 
sales-worthy product, the Committee 
should indicate the engineering require- 



ments of systems of different quality. 
In this way the theater industry can 
have the technical information needed 
on which to base its own course of com- 
petitive action. 

"It was pointed out, however, that 
in spite of our intent to operate pri- 
marily as an engineering group, the 
crystal-gazing aspect might, neverthe- 
less, be requested of us by the FCC. 
In such an event, an opinion would of 
course be determined, but in such a way 
as to distinguish it clearly from the 
factual engineering data which are to 
be the main concern of the Committee." 

Theater Engineering 

Society committee work in this field 
has been carried on from the very be- 
ginning, starting as a Theater Equipment 
Committee in 1916. From 1940 to 
1945 the Theater Engineering Com- 
mittee provided general directional re- 
sponsibility for several major Sub- 
committees which later became full 
fledged Engineering Committees, i.e., 
Projection Practice, Screen Brightness, 
Television Projection Practice, etc. The 
Committee on Theater Engineering Con- 
struction and Operation was one of 
these to become separately established 
in 1946, with this long title shortened 
to the present one of simply Theater 
Engineering in 1949. 

Leonard Satz of Raytone Screen Corp. 
served capably as Chairman of this 
Committee, starting in 1948; the present 
chairman is J. W. Servies of National 
Theater Supply. Projects studied by 
this group include theater carpets, 24 
air-conditioning, size and mounting 
characteristics of theater screens, and 
theater codes. A correlation of the 
latter as among the several states and 
cities would be of very great service to 
industry, and might promote worth- 
while standardization. 

Thus is concluded the description 
of the 18 Engineering Committees 
presently operating for the SMPTE. 



174 



September 1952 Journal of the SMPTE Vol. 59 



Further along engineering lines, the 
Society is a member of the Inter-Society 
Color Council and is represented there 
by a delegation of which Ralph M. 
Evans of Eastman Kodak is Chairman. 
Society representation is similarly pro- 
vided on the U.S. National Committee 
of the International Commission on 
Illumination, with Ralph Farnum of 
General Electric as Chairman. The 
most extensive of these extra-society 
engineering activities, however, is that 
with The American Standards Associa- 
tion, this being discussed in the following 
paragraphs. 

American Standards Association 

This is an association of standardizing 
bodies in many fields of industry, 
sponsored by industry, and issuing so- 
called American Standards. These 
Standards do not of themselves have 
any force in law, but are generally 
recognized as representing best practice, 
and so are frequently incorporated in 
purchase specifications by agreement 
between individual buyers and sellers. 
Elaborate safeguards are provided in 
the preparation of these standards, 
insuring the very careful review of all 
standards proposals by a sequence of 
authorities terminating in a Standards 
Council. Provision is also made for 
the periodic review of all existing 
American Standards so that obsolete 
material does not remain on the books. 

Standards in the field of motion pic- 
tures and in those aspects of television 
assigned the Engineering Committees of 
SMPTE are processed through ASA 
Sectional Committee PH22 on Motion 
Pictures, presently under the chairman- 
ship of Dr. D. R. White of Du Pont. 
This ASA Committee is authorized to 
consider proposals received from any 
reputable source, but, in practice, 
almost all of these originate in SMPTE 
or in the Motion Picture Research 
Council. In line with the simplification 
previously discussed, Committee PH22 
seldom conducts a technical study in the 



entire Committee, since the representa- 
tion is necessarily so broad that adequate 
technical coverage of any one specialized 
field is not possible. Subcommittees 
used to be created to enlist such talent 
as needed, but this is now handled 
through the Engineering Committees 
of SMPTE. Thus with respect to the 
processing of American Standards, Com- 
mittee PH22 is largely a policy group, 
concerning itself more with the need 
for a particular standard and whether 
or not an adequate consensus has been 
reached, rather than with the technical 
content. 

With the recently increased interest 
in world standards through Technical 
Committee 36 on Cinematography of 
the International Organization for 
Standardization (ISO/TC36), PH22 has 
now assumed an important new re- 
sponsibility. The Secretariat of this 
International Committee is held by the 
ASA, and the responsibility for express- 
ing the U.S. viewpoint, both respecting 
world standards proposals and in reply- 
ing to the proposals of other nations, 
naturally channels through PH22. 
Policy matters are decided there, and 
technical studies requested of the 
SMPTE Committees where needed. 
The first international meeting of ISO/ 
TC36 was held in New York City on 
June 9, 10 and 11, 1952, with PH22 
playing an important part in heading 
the U.S. delegation. U.S. proposals for 
consideration as International Standards 
were first recommended by the Engi- 
neering Committees of SMPTE, and the 
Chairmen of the committees concerned 
with these recommendations were in- 
cluded in the U.S. delegation headed 
by Dr. White. The Engineering Vice- 
President of SMPTE was chosen as 
chairman of this first formal meeting of 
ISO/TC36, and is most appreciative 
of having been given this opportunity 
to work with this very sincere and 
highly cooperative group. Delegates 
from Belgium, France, Germany and the 
United Kingdom worked with the U.S. 



F. T. Bowditch: Engineering Activities 



175 



group here to achieve substantial 
unanimity respecting a much greater 
number of so-called Draft Proposals 
than anyone had thought possible. 

Committee PH22 derives its authority 
from two sources. First, the Com- 
mittee is "sponsored" by the SMPTE. 
This is a conventional arrangement, 
typical of many other ASA Sectional 
Committees. The sponsor is responsible 
for the agenda, and submits his recom- 
mendation to ASA respecting the chair- 
man. He is ordinarily required to 
supply secretarial service, which is very 
capably done for PH22 by the very 
versatile Henry Kogel, SMPTE Staff 
Engineer. Kogel is unusually well fitted 
for this task, since he also serves as 
secretary for all the Engineering Com- 
mittees of SMPTE, previously described. 

Within the ASA structure, Com- 
mittee PH22 is one of five Sectional 
Committees under the general juris- 
diction of a Photographic Standards 
Board (PSB), of which Paul Arnold of 
Ansco is the Chairman. The other Com- 
mittees in this group are: 

PHI, Photographic Films, Plates and 

Papers; 

PH2, Photographic Sensitometry; 
PH3, Photographic Apparatus; and 
PH4, Photographic Processing. 

These four represent divisions of the 
earlier ASA Sectional Committee Z38 
on Photography, which became too 
cumbersome in its operations to con- 
tinue as a single group. When this 
reorganization of Z38 into four separate 
Committees was under consideration 
by the ASA, the creation of a new 
correlating Board was also proposed, 
to which these new PH committees 
would report in a manner conventional 
in the ASA with other groups. The 
SMPTE was asked to agree to a revision 
of the then independent status of ASA 
Sectional Committee Z22 on Motion 
Pictures, so that it too would report 
to the new correlating Board. This 
was agreed to, and the designation 



accordingly changed from Z22 to PH22. 
Objections were raised at the time to 
inserting another in the long chain of 
reviewing agencies between the technical 
working body on the one end and the 
Standards Council on the other. How- 
ever, SMPTE received assurance from 
the ASA that this was purely an organi- 
zational detail within ASA, and that 
the new Correlating Committee would 
exercise no significant authority over 
the affairs of PH22. Correlation is 
naturally required at some stage to 
prevent possible duplication of effort 
between PH22 and the four other PH 
Committees, and this the new Photo- 
graphic Standards correlating Board 
does with very good effect all around. 
Thus while the rules of procedure of the 
ASA give correlating Boards in general 
the right to exercise a considerable degree 
of authority, this is frequently not used, 
and it is anticipated that the existence of 
the PSB will have little effect on the 
operations of PH22, so long as the 
SMPTE does a competent job as 
sponsor. 

This then is the present picture of the 
activities in which the Engineering 
Vice-President represents the interests 
of the SMPTE. It is a continual 
pleasure to work with such a fine, 
cooperative group of technical people, 
and particularly with the very refreshing 
international experience with ISO/ 
TC36 so clearly in mind, it seems 
altogether tragic and unnecessary that 
similar progress is not made along 
political lines. The scientists, however, 
are showing an ever increasing concern 
in the study of human reactions, for 
example in their interest in many phases 
of the science of color, and the determi- 
nation of preferred motion picture 
viewing conditions so they may yet 
bring their talents and impartial scien- 
tific viewpoints to bear on the trouble- 
some social problems of the world. 
Having seen the fine cooperative give- 
and-take in our many Committees, with 



176 



September 1952 Journal of the SMPTE Vol. 59 



axe-grinding at a negligible minimum, 
one is at least led to hope. 

Finally, I wish to express my great 
indebtedness to the several Chairmen 
mentioned previously, and to the almost 
300 Committee members, whose un- 
selfish cooperation has made this work 
possible; also, to Society headquarters 
where Boyce Nemec maintains a most 
efficient organization and Henry Kogel 
strives manfully and with very good 
effect to keep on top of his even score 
(or is it more?) of secretarial responsi- 
bilities. The contribution of my own 
employer, The National Carbon Com- 
pany, in granting me the time and 
expense monies necessary to the conduct 
of this very pleasant work, is also grate- 
fully acknowledged. 

References 

1. "A restatement of policy," Jour. 
SMPTE, 54: 233, Feb. 1950. 

2. "Characteristics of color film sound 
tracks," ibid., 54: 377, Mar. 1950. 

3. "Principles of color sensitometry," 
ibid., 54: 653-724, June 1950. 

4. C. F. Jenkins, "Society history," 
Trans. SMPE, No. 7: 6-8, Nov. 1918. 

5. W. F. Kelley and W. V. Wolfe, 
"Recent studies on standardizing the 
Dubray-Howell perforation for uni- 
versal application," Jour. SMPTE, 
56: 30-38, Jan. 1951; W. Hill, 
"Modified negative perforation," ibid., 
57: 108-123, Aug. 1951; "Proposed 
American standard," ibid., 57: 275- 
278, Sept. 1951. 

6. F. H. Richardson, "Projection room 
and its requirements," Trans. SMPE, 
No. 7: 29-37, Nov. 1918. 

7. "Television test film," Jour. SMPTE, 
54: 209-218, Feb. 1950. 

8. C. Townsend, "New all-purpose film 
leader," ibid., 56: 562-567, May 1951. 

9. "Recent American standards for 16 
and 8mm emulsion position," Jour. 
SMPE, 49: 547-557, Dec. 1947. 



10. "Panel discussion on emulsion position 
of 16mm positives," Norwood Sim- 
mons, Moderator, SMPTE Conven- 
tion, October 17, 1951. A mimeo- 
graphed transcript, 46 pp., is available 
upon request to Society headquarters. 

11. K. Shaftan, "A survey of high-speed 
motion picture photography," Jour. 
SMPTE, 54: 603-626, May 1950; 
"Bibliography on high-speed photog- 
raphy," ibid., 56: 93-111, Jan. 1951. 

12. "High-speed photography question 
box," ibid., 55: 122, July 1950; ibid., 
55: 328, Sept. 1950. 

13. "Chemical corner," ibid., 57: 87-88, 
July 1951; ibid., 58: 272-273, Mar. 
1952. 

14. M. A. Hankins, "Motion picture studio 
lighting committee report," ibid., 56: 
205-213, Feb. 1951. 

15. W. W. Lozier, "Screen brightness 
committee report," ibid., 54: 756-757, 
June 1950; "Report on screen bright- 
ness committee theater survey," ibid., 
57: 238-246, Sept. 1951; "Further 
report on screen brightness committee 
theater survey," ibid., 57: 489-493, 
Nov. 1951. 

16. "Symposium on screen viewing fac- 
tors," ibid., 57: 185-237, Sept. 1951. 

17. "Proposed 16mm and 8mm sprocket 
standards," Jour. SMPE, 51: 437-440, 
Oct. 1948. 

18. "Recommendations for 16mm and 
8mm sprocket design." Jour. SMPTE, 
54: 219-228, Feb. 1950. 

19. Loren L. Ryder and Bruce H. Denney, 
"Magnetic sound track placement," 
Jour. SMPTE, 58: 119-136, Feb. 1952 
(includes Discussion, pp. 127-136). 

20. "Motion picture standards," Trans., 
SMPE, No. 4: 8-9, July 1917. 

21. F. T. Bowditch, "Report of SMPE 
standards committee," Jour. SMPE, 
51: 230-241, Sept. 1948. 

22. D. Hyndman, "Theater television 
committee report," Jour. SMPTE, 
56: 124-125, Jan. 1951. 

23. "Theater television and the FCC," 
ibid., 57: 78-80, July 1951. 

24. "Theater carpeting manuals avail- 
able," ibid., 54: 646-647, May 1950. 



F. T. Bowditch: Engineering Activities 



177 



Explosive Argon Flashlamp 



By G. H. WINNING and H. E. EDGERTON 



Oscillo graphic measurements of the light output from argon explosive flash- 
lamps show that the flash duration is about 1 jusec for a 0.5-cm thickness of argon 
over the end of a cone of cast pentolite 2 in. in diameter. The peak light out- 
put is about 200 million cp, and the total output about 200 cp sees. Photographs 
of the argon lamps were made with a magnetooptic shutter having an effective 
exposure of about 1 pisec to show the space origin of the light. 



HE PHOTOGRAPHY of detonations by 
means of an ordinary single-exposure 
camera has been difficult to accomplish 
for two reasons. First, either the light 
from the detonation of high-temperature 
explosives is so actinic as to fog the film; 
or the light from the detonation of rel- 
atively low-temperature explosives such 
as those of the permissible, coal-mining 
type, for example, is insufficient to affect 
the film in the brief exposure time re- 
quired to stop the motion. Second, 
although conventional short-flash elec- 
tronic flashlamps might be considered 
for some purposes, their use is expensive 
because the lamp is destroyed by the 
explosion. 

The second difficulty may be over- 
come, for problems where the subject is 
not excessively large, by the use of 



Presented on April 23, 1952, at the Society's 
Convention, at Chicago, 111., by C. H. 
Winning, E. I. duPont de Nemours & 
Company, Explosives Dept., Eastern Labo- 
ratory, Gibbstown, N.J., and H. E. 
Edgerton, Massachusetts Institute of Tech- 
nology, Electrical Dept., Cambridge 39, 
Mass. 



another explosive to produce light at the 
proper time. A relatively inexpensive, 
expendable, flash-producing, explosive- 
activated lamp is described here. The 
objects of this paper are, first, to present 
oscillographic measurements of the light 
output from an argon-filled explosive 
flashlamp and, second, to present se- 
quence photographs of the exploding 
lamp itself for correlation with the 
oscillograms. 

Successful photography of self-lumi- 
nous subjects may be accomplished by 
the use of Kerr cells, Faraday-effect 
shutters, and by image-converter tubes. 
The series of photographs published here 
of the explosive argon flashlamp during 
explosion were taken with the Rapa- 
tronic shutter (Faraday magnetooptic 
type). 

Argon Flashlamp 

In 1937 Michel-Levy and Muraour 
published a series of pictures which 
illustrated that rapidly occurring events, 
such as the deformation of a lead block 
by an explosive, could be photographed 
at desired instants during the process 
through proper use of the short, intense 



178 



September 1952 Journal of the SMPTE Vol. 59 



luminosity of the shock wave generated 
in argon gas by a small amount of a 
brisant explosive. 1 

Shock-wave flashes of about 4- to 20- 
/xsec (4 to 20 X 10~ 6 sec) duration and 
300-600 million cp intensity were pro- 
duced by detonating 0.4-5.0 cm 3 of a 
brisant explosive (tetranitromethane plus 
toluene) in the end of a small, grooved 
brass cylinder, above which was a cello- 
phane tube filled with the argon. The 
cellophane tube and the brass cylinder 
had the same diameters, namely 8 mm or 
more. The vertical cellophane cylinder 
of argon traversed by the luminous shock 
wave had a height of about 8 cm. 2 * 3 
Apparently the selected materials and 
dimensions favored the production of 
brief, intense luminosity. 

Later investigators who employed the 
argon flashlamp in photographing vari- 
ous explosive phenomena used modified 
forms of the lamp. Shepherd reported 
use of a lamp consisting of approximately 
^ oz of pressed tetryl inside a cardboard 
cylinder 2 in. in diameter. The end of 
the cylinder had a cellophane window. 4 
The duration of luminosity of the flash- 
lamp was estimated to be 2-4 /*sec. The 
pictures, which were taken by either 
front or back lighting (silhouette), illus- 
trated that the light from the argon 
flashlamp, even though spread over the 
expanse of the subject at different 
selected stages in the explosion process, 
was much more brilliant than the hot gas 
from the permissible-type explosives. 
U.S. military investigations during World 
War II included photographic studies of 
underwater explosions, which required 
the development of lamps suitable for 
(1) the illumination of gas bubbles from 
explosions at different depths and (2) the 
illumination of relatively small, high- 
velocity, demolition explosives detonat- 
ing relatively near the camera. In order 
to obtain flashes of high intensity and 
short duration, attention was given to 
both the surface area of the charge 
generating the shock wave at a given in- 
stant and to the thickness of the argon 



layer traversed by the shock wave. 
Both spherical and conical cast pentolite 
charges were employed. 6 It was found 
that both the duration and the intensity 
of the illumination increased with the 
thickness and the area of the argon gas 
layer, but details about the methods and 
results have not been published in the 
open literature. 

The present paper includes micro- 
second photographs and oscillograph re- 
productions which show the character- 
istics of the brief flash of intense light de- 
veloped by a conical explosive charge in 
an experimental type of flashlamp used 
at Eastern Laboratory. 

Experimental 

Photographs of the argon flashlamp 
were made with a one-microsecond 
Rapatronic shutter. 6 The shutter is 
triggered by the light from the explosion 
by means of a photoelectric cell (RCA 
929) and an adjustable time-delay cir- 
cuit. 

The Rapatronic shutter consists of 
crossed polarizers between which is a 
slug of extra-dense flint glass as shown in 
Fig. 3. The shutter is opened by causing 
the plane of polarization to rotate in the 
glass (Faraday effect) by an axial mag- 
netic field. 

The 1-jusec exposure is produced when 
a 24-kv, 0.125-/xf capacitor is discharged 
through a triggered air gap into a nine- 
turn coil around a slug of extra-dense 
flint glass 1 in. in diameter. The plane 
of polarization of the light passing 
through the glass is rotated by the mag- 
netic field. A doublet camera lens of 
about 6-in. focal length was used in 
front of the Rapatronic shutter. Visual 
focusing was accomplished by rotating 
one of the polarizers that normally are 
crossed on opposite ends of the flint glass. 

The light-time oscillographic trace 
was displayed on a Du Mont Type 256A 
ranging oscillograph, and a photograph 
was made to record the transient. Light 
from the argon explosion was allowed to 
fall on the cathode of an RCA Type 929 



Winning and Edgerton: Explosive Argon Flashlamp 



179 





D 



Fig. 1. Explosion of argon flash lamp. 

A. Lamp with watch glass 0.5 cm ahead of conical pentolite charge. 
"Primacord" initiator and argon gas line are at rear. 

B. Frontal lamp flash about 0.5 jtsec after attaining maximum intensity. 

C. Condition about 3 /zsec after maximum flash. 

D. Condition about 7 jusec after maximum flash. 



phototube (S4 cathode) which had a 
1000-ohm load resistor and a plate sup- 
ply of 2000 v. The high plate voltage 
was necessary to assure that current and 
light were proportional at the large 
values of current. The time constant of 
the output circuit was estimated to be 
less than 0.1 j*sec. 

Calibration of light deflection was 
made by the use of a General Radio 
Strobolume which produces about 10 
million peak beam candlepower. 

The explosive flashlamp (Fig. 1A), 
whose performance is reported in this 



paper, consisted of a 2-oz conical, cast 
pentolite (50-50 PETN and TNT) 
charge within a 2.5-in. diameter glass 
tube containing argon. The front of the 
conical charge (contained in a glass 
funnel) was curved to conform with the 
curvature of the watch glass sealed over 
the front of the lamp. The desired 0.5-, 
1 - or 2-cm spacing for argon between the 
explosive charge and the watch glass was 
fixed by using a spacer made from a thin 
gelatin capsule. The pentolite charge 
was initiated at the rear apex of the cone 
by means of the "Primacord" detonating 



180 



September 1952 Journal of the SMPTE Vol. 59 




U SEC. - TIME 



Fig. 2. Luminosity-time curves for argon flashlamps. 



Symbol 



Thickness of argon 

layer at front of 

lamp, cm 



0.5 
1.0 
2.0 



fuse which entered the charge through 
the stem of the funnel. The air in the 
lamp was flushed out with argon ad- 
mitted through a tube at the rear of the 
lamp. 

Microsecond Photographs 

Figure IB shows a picture of the argon 
flashlamp about 0.5 /xsec after the 
maximum intensity of the flash. It may 
be observed that the luminosity is slightly 
more intense, and perhaps near the 
maximum, around the circumference of 
the face, that is, in the narrow outer 
region slightly removed from the im- 



mediate frontal effect of the explosive. 
(The front of the lamp had an inside 
diameter about 0.5 in. greater than that 
of the explosive charge.) Also evident 
in the picture is what appears to be a 
small hole at the center and front of the 
charge where a 0.5-cm spacer was lo- 
cated. (This spacer was made of cork 
rather than gelatin.) No light is evident 
lateral to the direction of propagation of 
the detonation at the instant of this 
photograph. 

Figures 1C and ID are pictures of the 
lamp taken about 3 and 7 /xsec, respec- 
tively, after the highly actinic flash from 
the front. In the approximate exposure 
time of 1 ptsec, the hot explosive gases are 
not sufficiently actinic to appear lumi- 
nous; and accordingly, the gas cloud 
pouring out of the front appears black. 
As the explosion gas spreads out laterally, 
it obscures the lateral actinic flash in the 



Winning and Edgerton: Explosive Argon Flashlamp 



181 






-DENSE FLINT GLASS 
-P2 



FILM 




I MICROSECOND 
MAGNETO OPTIC 
SHUTTER 



PHOTOCELL TRIP 



Fig. 3. Rapatronic magnetooptic camera arrangement used to photograph 
the argon flashlamp. 



argon, that is, at the rear portion of the 
lamp and around the apex of the conical 
charge. 

Figure 2 is a scaled reproduction of the 
oscillograms obtained on explosive flash- 
lamps having frontal argon atmospheres 
0.5, 1 and 2 cm thick. No corrections 
have been made for adjustment to refer- 
ence oscillograms obtained with a 
standard 1 million cp lamp prior to each 
experimental shot. With 0.5 cm of 
argon the major portion of the flash was 
over in 1 jusec or less. The exact shape 
of the increasing and decreasing lumin- 
osity curve could not be ascertained on 
the recorded scale. The average of the 
three records for 0.5 cm of argon, by 
comparison with records of a standard 1 
million cp lamp, reveals a peak intensity 
of about 225 million cp. The flash- 
lamps with 1 cm of argon had a duration 
of 2 /isec for the maximum luminosity, 
and the initial rate of increase in lumin- 
osity appeared to be approximately that 
for the 0.5-cm argon layer, but there was 
a slightly higher maximum. The maxi- 
mum intensity was 250 million cp. With 
2 cm of argon the first and major portion 
of the luminosity increase was practically 
as rapid as for the two preceding spac- 
ings; however, the duration of the 
maximum luminosity was about 4 /usec, 
and the peak intensity was about 300 
million cp. The uncertainty of the refer- 
ence standard for this record makes the 



maximum a littie more uncertain than 
for the others. A small, trailing lumin- 
osity was evident about 1 or 2 jusec after 
the main flash in all cases. This phe- 
nomenon could be attributed to a lagging 
luminosity at the circumference, as 
indicated in Fig. IB. 

Discussion of Results 

The oscillograms indicate that the 
duration of the main flash from the argon 
flashlamp, as measured by the writers, 
is about 2 ^isec for each centimeter of 
thickness of the argon layer. The 
maximum intensity is developed after 
one-half to three-quarters of this time 
interval has elapsed. The measure- 
ments cover argon layers 0.5 to 2 cm 
thick. The time for development of the 
maximum intensity probably is related 
to the time required for the shock wave 
in the argon to reach the front of the 
lamp. 

The average peak intrinsic brilliancy 
of the sheet of light-radiating argon gas 
is calculated by dividing the peak light 
(225 million cp) by the area (33 sq cm). 
This value is 6.8 million cp/square 
centimeter. Flash bombs with larger 
output would supposedly be of larger 
argon area. Some care might be re- 
quired to initiate the flash of all portions 
of the sheet of gas at the same instant. 

The duration and light-intensity data 
of Muraour et al. 2 > 3 closely resemble 



182 



September 1952 Journal of the SMPTE Vol. 59 



those presented here, but these investi- 
gators did not determine the time- 
intensity curve. They calculated the 
average intensity from the measured 
photoactinic effect on film (by compari- 
son with a standard) and from knowledge 
of the duration determined either by 
photographing rapidly moving objects of 
known velocity, or by use of rotating- 
drum-camera pictures. 

Continuing experimental studies of 
explosive flashlamps should consider 
other rare gases such as krypton, neon 
and xenon as well as other explosives for 
creating the shock wave. Since xenon 
is preferred to argon in electronic flash- 
lamps, it is assumed that it might be 
better in explosive lamps. 

Photography With Argon Flashlamp 

Consider now the photographic use of 
the l-jtisec argon flashbulb as described. 
The following relationship is often useful 
in arriving at a preliminary set of ex- 
posure conditions: 



DA = 



where 

D = lamp-to-subject distance in feet 

A = aperture of lens 

Q, = total light output in lumen- 
seconds 

M = reflector factor 

K = a constant which depends upon 
the type of film used and the processing. 

For the argon flashlamp without a re- 
flector, M = 1 and Q, = 10 X cp-sec 
= 2000 Im-sec (approximately). K is 
about 0.25 for fast film. Now if A is 
selected to be about//4.5, then the lamp- 
to-subject distance, D, can be calculated. 
D equals about 5 ft. 

This result must be used with judg- 
ment, depending upon the reflectivity of 
the subject that is being photographed. 
Often a sheet of white cardboard imme- 



diately back of the subject is very useful in 
giving a silhouette of darker portions of 
the subject. 

The contrast of photographs is usually 
low when they are taken with blue light 
of short exposure time. This lack of 
contrast can be corrected by a longer de- 
velopment time or the use of a more 
vigorous developer. 

References 

1. A. Michel-Levy and H. Muraour, 
"Photographs of phenomena accom- 
panying explosion of a brisant explo- 
sive," Compt. rend., 204: 576-579, 1937. 

2. H. Muraour, "Shock waves and deton- 
ation luminosities," Chimie & Industrie, 
47: 3-15, 1942. 

3. H. Muraour, A. Michel-Levy and E. 
Vassy, "A flash source for photographic 
purposes," Rev. optique, 20: 161-164, 
1942. 

4. Safety in Mines Research Board, 25th 
Annual Report, 1946, H. M. Stationery 
Office, London, 1947, pp. 29-31. 

W. C. F. Shepherd, "Coal mining ex- 
plosives; present day research of the 
Safety in Mines Research and Testing 
Branch, Ministry of Fuel and Power," in 
Proceedings; Fifth International Conference 
of Directors of Mine Safety Research, Bull. 
489, U.S. Bureau of Mines, U.S. 
Government Printing Office, Washing- 
ton, D.C., 1950. 

5. J. E. Eldridge, P. M. Fye and R. W. S. 
Spitzer, "Photography of underwater 
explosions," Office of Scientific Re- 
search and Development, Report 6246, 
1947 (P.B. 96667, Office of Technical 
Services, U.S. Department of Com- 
merce, Washington, D.C., 93 pp.) 
See also: Paul M. Fye, "The high-speed 
photography of underwater explosions," 
Jour. SMPTE, 55: 414-424, Oct. 1950. 

6. H. E. Edgerton and C. W. Wyckoff, 
"A rapid-action shutter with no moving 
parts," Jour. SMPTE, 56: 398-406, 
Apr. 1951. 

7. H. E. Edgerton, "Light-meter uses with 
electronic flash," PSA Jour., Part II, 
Photographic Science and Technique, 16: 
6-10, Jan. 1950. 



Winning and Edgerton: Explosive Argon Flashlamp 



183 



Integrating-Type 
Color Densitometer 

By FRANK P. HERRNFELD 



This color densitometer is for making diffuse density measurements in the 
blue, green and red, as well as visual bands. This densitometer utilizes an 
integrating bar for gathering the light, therewith greatly increasing the 
sensitivity as compared to other methods presently used. 



JL HE REQUIREMENTS for a color densi- 
tometer are very similar to those of a 
black-and-white unit. Enumerated ac- 
cording to importance, they are: 

1. reproducibility of readings, 

2. simplicity of operation, 

3. sufficient range and flexibility, 

4. accuracy, and 

5. electrical calibration. 

Reproducibility of reading was ac- 
tually the hardest part of our design 
problem. We found that a stable 
amplifier alone was not the answer. 
It calls for rugged mechanical construc- 
tion, the selection of the proper photo- 
electric cell, stable optical filters, a 
color-corrected optical system, and many 
small features too numerous to mention. 
When the desired stability was reached, 
the unit was finished. 



Presented on April 24, 1952, at the Society's 
Convention at Chicago, 111., by Frank P. 
Herrnfeld, Frank Herrnfeld Engineering 
Corp., 5880 Blackwelder St., Culver City, 
Calif. 



Figure 1 shows the optical schematic 
of the instrument. As light source we 
use a General Electric 4AT8-34 lamp 
rated at 8.5 v 4.0 amp. In operation 
the lamp burns at 7.5 v, has an approxi- 
mate color temperature of 3000 K, and 
a life expectancy of 500 hr. In stand- 
by condition, the voltage is reduced to 
5.0 v. A special socket insures proper 
electrical contact and placement on the 
optical axis. Both vertical and hori- 
zontal adjustments of the lamp socket 
are provided. 

The condenser lens has full achromatic 
correction and focuses the filament of 
the lamp onto an aperture. An inter- 
rupter wheel and an infrared absorbing 
filter are located between the condenser 
lens and the aperture. The interrupter 
wheel, driven by a 3600-rpm synchro- 
nous motor, modulates the light beam 
at the rate of 360 cycles/sec, making 
the use of a stable a-c amplifier possible. 

The infrared filter is a Corning No. 
9780 2^-mm thick glass and is always in 
the light beam. It has the dual purpose 
of (a) reducing the heat rays reaching 



184 



September 1952 Journal of the SMPTE Vol. 59 




OBJECTIVE LENS 






FILM PLANE 



INTEGRATING BAR 
\J RE.CELL 
Fig. 1. Optical schematic of the integrating-type color densitometer. 



the photosensitive surface of the photo- 
electric cell in the red and visual setting 
of the densitometer and (b) eliminating 
undesirable near-infrared light reaching 
the photoelectric cell passed by all blue 
and green filters. 

Either of two apertures can be used 
for making density measurements. One 
is a round one, illuminating a circle of 
about -^ in. in diameter at the film 
plane; the other is rectangular, illumi- 
nating a 0.015 by 0.125 in. area. The 
round aperture is meant for general 
work and the rectangular one for the 
measurement of variable-area sound 
track. 

A fully achromatic corrected objective 
lens focuses the aperture onto the film 
to be measured. The color and visual 
filters and a front-surfaced mirror are 
located between the aperture and the 
objective lens. 

Four filters are mounted in a wheel. 
A neutral density is mounted with each 
filter to bring the photoelectric cell 
output to the same value. This mini- 
mizes zero adjustment when going from 
one color band to another. An inte- 
grating bar collects the light passing 



through the film and delivers it to the 
photoelectric cell. 

In checking all available commercial 
photoelectric cells, we found only two 
that lend themselves readily to the 
measurement of density, namely the 
RCA 1P42 and 929, or the equivalent 
in other makes. 

We found that the 1P42 had an un- 
desirable lag and color fatigue in the 
blue and green bands with the amount 
of light necessary to measure to a color 
density of 4.0. This can be partially 
overcome by raising the anode voltage 
above the ionization potential (18 v). 

Raising the anode voltage sufficiently 
to overcome the fatigue problem raises 
two others: (1) If any trace of gas is 
left in the photoelectric cell, the cell 
will become nonlinear in the low density 
range when the greatest amount of light 
is present. (2) It will raise the dark 
current which means more noise, re- 
ducing the small margin between signal 
to noise in tffe high density range. 

The 929 photoelectric cell has a 
greater output for a given light input, 
and does not seem to suffer from the 
above-mentioned shortcomings of the 



Frank P. Herrnfeld: Color Densitometer 



185 



1P42, but the photosensitive surface is 
too far from the film to make the tube 
a good receiver. Means to gather all 
the light, coming through the sample 
tested have to be provided. This is 
important when measuring the density 
of negatives, as all silver images and cyan 
dyes show a greater density when meas- 
ured in a spectral system. 

We know of only three methods to 
measure true diffuse density: 

1. placing the sample to be measured 
directly in contact with the photosensi- 
tive circuit, 

2. utilizing a sphere, up to now con- 
sidered the standard in the motion pic- 
ture industry, and 

3. utilizing an integrating bar. 

The first method, theoretically the 
most simple, is nearly impossible in 
actual practice. The second method, 
excellent in black-and-white measure- 
ments, introduces too much loss into the 
system. Depending upon the method 
of coating and the size of the sphere, 
a loss of light equivalent to inserting a 
density between 1.3 and 1.5 is the 
minimum obtainable in practice. Add- 
ing this loss to the insertion loss of the 
optical filters will restrict any instrument 
using a design similar to ours to a maxi- 
mum density range of 3.0. 



The third method, the integrating 
bar with a diffusing surface toward the 
film to be measured, retains all the ad- 
vantages of a sphere. It introduces a 
loss of light equivalent to inserting a 
density of 0.6, making diffuse color 
density measurements of 4.0 possible. 

Table I shows the measurements 
obtained from three common sound 
track emulsions when measured with a 
sphere, integrating bar and spectral 
type of instrument. For comparison 
they were measured with a sphere-type 
densitometer having a visual-type color 
characteristic and the visual filter on 
our Model 1503A with and without 
the integrating bar. 

The differences between readings of 
the sphere type and 1503A with the 
integrating bar are due to difference in 
spectral sensitivity of the two instru- 
ments. 

Figure 2 shows the spectral distribu- 
tion of the light source and the visual 
filter with this light source compared 
to an average eye characteristic. 

Figure 3 shows the spectral distribu- 
tion of the three combination color 
filters with the light source shown in 
Fig. 2. 

As mentioned before, the Corning 
No. 9780 infrared absorbing filter is 



Table I. Comparison Test of Three Common Sound-Track Emulsions 
(using Pathe 2B Sensitometer). 

E.K. 5373, 4-min dev. DuPont 836, 5-min dev. DuPont 831, 9-min dcv. 



Step 



RA- RA- RA- 

1100B 1503A 1503A-S 1100B 1503A 1503A-S 1100B 1503A 1503A-S 



1 


0.04 


0.03 


0.05 


0.05 


0.05 


0.07 


0.09 


0.09 


0.13 


3 


0.06 


0.05 


0.08 


0.06 


0.06 


0.09 


0.11 


0.12 


0.15 


5 


0.11 


0.09 


0.16 


0.12 


0.10 


0.19 


0.18 


0.19 


0.26 


7 


0.19 


0.17 


0.29 


0.20 


0.17 


0.31 


0.40 


0.44 


0.56 


9 


0.33 


0.28 


0.48 


0.33 


0.29 


0.50 


1.00 


1.08 


1.37 


11 


0.49 


0.46 


0.71 


0.53 


0.48 


0.75 


2.05 


2.16 


2.63 


13 


0.69 


0.66 


0.95 


0.77 


0.71 


1.06 


3.18 


3.28 


3.75 


15 


0.90 


0.88 


1.21 


1.07 


1.00 


1.43 


3.87 


3.97 


4.+ 


17 


1.12 


1.10 


l.47 


1.39 


1.33 


1.80 








19 


1.31 


1.31 


1.67 


1.71 


1.67 


2.13 








21 


1.45 


1 .47 


1.81 


1.94 


1.95 


2.38 








Gamma 


0.69 


0.69 


0.88 


0.96 


0.96 


1.17 


3.66 


3.66 


4.68 


Q 


1.27 






1.22 






1.28 







186 



September 1952 Journal of the SMPTE Vol. 59 




c/ 



-1.0 



! -2.0 



500 MILL! MICRONS 600 700 

Fig. 2. Response of light source visual filter and eye. A: tungsten 
2780 K+Corning 9780 +929 photoelectric cell; B: light source + Corning 
3389; C: average human eye. 



40O 




400 500 VIILLI MICRONS 600 700 

Fig. 3. Response of color filters. A: light source +Corning 3389+5113; B: light 
source -fCorning 3486+4010; C: light source +Corning 2408. 



Frank P. Herrnfeld: Color Densitometer 



187 



V3 



V4 





V6 




Fig. 4. Amplifier schematic. 



Ml indicating instrument 
PI zero density adjustment 
P2 range selector 
P3 1.0 density adjustment 
VI 929 photoelectric cell 



V2 12SF5 amplifier 

V3 12SJ7 amplifier 

V4 12SJ7 amplifier 

V5 12H6 rectifier 

V6 12SL7 vacuum-tube voltmeter 



always in the light beam. The visual, 
blue, green and red filters are located 
in an indexed color wheel. The blue 
filter consists of two Corning glasses, 
Nos. 5113 and 3389; the green filter 
of two Corning glasses, Nos. 4010 and 
3486; and the red of one Corning glass 
No. 2408. 

The minimum bandwidth of the sys- 
tem is fixed by the filters having the 
least amount of output in conjunction 
with the photoelectric cell used. In this 
case, the Corning glasses Nos. 9780 and 
2408, with the 929 photoelectric cell 
and the lamp burning at 3000 K de- 



termine the bandwidth. The green and 
blue filters are chosen to give a similar 
characteristic having greatest transmis- 
sion at 540 and 445 rmz respectively. 
Corning glasses were chosen for their 
greater permanence. 

Figure 4 shows the electrical schematic 
of the amplifier. The zero adjustment 
is in the cathode of V2, the first amplifier 
tube, and has a range of about 8 db, 
equivalent to a density change of 0.40. 
P2 is a 20 db per step pad, having a 
total range of 100 db, giving ranges of 
to 1, 1 to 2, 2 to 3, and 3 to 4. Also 
included is the 1.0 calibration position. 



\ 



-20 



-30 



20 



100 1000 

FREQUENCY IN CYCLES PER SECOND 
Fig. 5. Frequency response of amplifier. 



10000 



188 



September 1952 Journal of the SMPTE Vol. 59 



V3 and V4 are a stabilized amplifier of 
constant gain. V5 and V6 comprise a 
balanced vacuum-tube voltmeter. Line 
voltage changes are balanced out and 
will not affect the readings. This does 
not mean that the instrument should 
be used without a voltage regulating 
transformer, as changes in the supply 
for the light source will greatly affect 
the stability of reading. 

The indicating meter Ml has special 
pole pieces to give the instrument an 
approximately linear scale with logarith- 
mic input over a 10 to 1 range. The 
circuit is arranged in such a manner 
that with an increase in current, the coil 
of the meter moves into a magnetic 
field of lesser density. This arrange- 
ment prevents a runaway condition and 
makes for a better instrument. P3 is 
the 1.0 calibrating adjustment. 

Figure 5 shows the frequency response 
of the amplifier section V3 and V4. 
This characteristic is caused by the 
tuned circuit in the cathode circuit of 
V3. The peak transmission corresponds 
to the frequency of the interrupter 
wheel in the light beam and eliminates 



to a great extent errors in reading due 
to stray light reaching the photoelectric 
cell. 

The filaments of all tubes are fed from 
a direct current source. The anode 
voltages on the photoelectric cell and of 
V2 are sufficiently low to eliminate any 
noise and nonlinearity due to gas present 
in the tubes. 

Figure 6 shows the finished instru- 
ment. The unit is made to fit into a 
table or desk with the power unit to be 
mounted out of the way of the operator. 
All controls are located on top of the 
panel. 

Upon completion, the unit was tested 
with several different lamps as light 
source. Reproducibility of readings 
was checked over a four-week period. 
The first two weeks the unit was checked 
each working day by the hour on the 
hour, allowing a 5-min warm-up period 
before making a reading. The instru- 
ment was shut off after each test. The 
latter two weeks the instrument was left 
on continuously. 

The readings thus obtained were in 
all instances within 0.02 of the original 




Fig. 6. Model 1503 A color densitometer. 
Frank P t Herrnfeld; Color Densitometer 



189 



measurement. Aging or changing of 
the lamp had no influence on the 
readings. 

The different density ranges and 
calibrations are selected by five push 
buttons plainly marked in front of the 
meter case. The film strip is held in a 
step-calibrated carriage, allowing easy 
selection of different tablet steps. After 
a 15-min warm-up period, recalibration 
is seldom necessary. 

The maximum range of the instru- 
ment is sufficient for all measurements 
encountered in the motion picture 
industry. Selection of the proper filter 
is simple and sure. All readings taken 
are diffuse readings and no change of 
location of the photoelectric cell is 
necessary. 

The absolute accuracy of reading, 
compared to a sphere-type and visual- 



type instrument, is sufficiently close for 
all purposes for which the instrument 
may be used. A 20-db signal-to-noise 
ratio on its highest reading, at a density 
of 4.2, guarantees accuracy over the 
complete range. The bandwidth of 
each of the three color filters is suffi- 
ciently narrow, and the suppression of 
all unwanted radiation sufficient to give 
an insertion loss of more than the 
equivalent of a density of 7.0 to white 
light when any two of the three filters 
are placed into the light beam at the 
same time. 

The instrument is calibrated elec- 
trically. The accuracy thus obtained 
is only a function of how much care 
has been taken in doing it. 

Several of these instruments are now 
in commercial service and have given 
consistent results. 



190 



September 1952 Journal of the SMPTE Vol. 59 



Transmission Color 
in Camera Lenses 

By PHILIP T. SCHARF 



The color contribution of a lens has been defined in terms of its transmittance 
density at 400 and 700 m M . It is proposed that the difference in the densities 
at these two wavelengths be held to 0.05 03 for motion picture camera lenses; 
0.05 d= .05 for other camera lenses. To prevent the curve from being too highly 
inflected between these two points an additional requirement is that the mini- 
mum density between 400 and 700 m/x differ from the density at 700 m^t by no 
more than 0.04 density units. It has been found convenient to describe 
quantitatively the glass absorption by a term called "color index." A simple 
method of determining the combined effect of glass absorption and surface 
coating is outlined. 



-L HERE HAS BEEN considerable interest 
in recent years in the subject of camera 
lens transmission. Prior to the advent 
of antireflecting coatings it was not un- 
heard of to have light losses amounting 
to as much as 50%. With present-day 
coated lenses, however, losses greater 
than 10% are seldom encountered. In 
terms of lens aperture this means that 
the loss of light with a coated lens does 
not exceed J of a stop. While there may 
still be reason for occasionally investi- 
gating the overall light loss of a coated 
lens, other variables in the photographic 
process will generally mask this ^ of a 
stop. On the other hand, the color of 
the light transmitted by camera lenses 

A contribution submitted June 17, 1952, 
by Philip T. Scharf, Process Development 
Dept., Hawk-Eye Works, Eastman Kodak 
Co., Rochester, N.Y. 



has caused much less interest, but in 
present-day practices it is probably more 
important than the overall white light 
transmittance. The increased interest 
in color photography is responsible for 
the importance of this color factor. 
Interchangeable lenses on cine cameras 
have made it possible for the photog- 
rapher to perform a very critical test for 
the uniformity of color in his lenses. In 
this case the same scene, the same film, 
and the same processing variables are 
maintained while only the lens is varied. 
This means that if the same exposure is 
used, the only variable is the color of the 
lens. We wish to center our attention on 
this subject of color variations occurring 
in lenses, and to investigate methods of 
minimizing this variation. 

There are two distinct factors con- 
tributing to the color of a lens. The 
first is the color of the glass itself. This 



September 1952 Journal of the SMPTE Vol. 59 



191 



0.10 



Blue coating 



Glass absorption 
Simple lens Complex lens 



Magenta 
coating 




400 



700 



500 600 

Wavelength in m/^ 

Fig. 1. Transmittance losses from glass absorption and coated surface reflection. 



color, generally yellowish, is caused by 
the ultraviolet absorption band of glass. 
Modern experiments have proven that 
in most optical glasses the visual color is 
a function of impurities present in the 
raw materials. At some future date, 
production quantities of all the common 
optical glasses may be available free of 
color. Until then we must learn how to 
use existing glasses. We have made a 
fairly extensive study of all the commonly 
used glasses from many sources. Two 
important findings that have come from 
this study are that there is a considerable 
difference between manufacturers and 
that the sources supplying color-free 
glasses appear to be able to maintain 
their quality. These findings have en- 
abled us to put a certain degree of con- 
trol over this first source of color in a 
lens. 

It is generally recognized that the 
antireflecting coatings impart a degree of 
color to the transmitted light. If we 
observe the light reflected from different 
thicknesses of these coating films we see 
that the thinner films are yellowish or am- 
ber, the thicker ones bluish, with magenta 



films lying in between. The yellow reflec- 
tion means that less blue light is reflected 
than red or green which in turn can be 
interpreted as meaning that more blue 
light is transmitted. Likewise the ma- 
genta coating means more green light 
is transmitted and the blue coating 
means more yellow light is transmitted. 
Since coatings do transmit light selec- 
tively we have here the second con- 
tributing source of color in the lens. An 
advantage can obviously be gained if 
we can get these two factors to cancel one 
another. Figure 1 is a plot of the two 
color-contributing factors in terms of 
wavelength and transmittance density. 
It can be seen that the curve shapes are 
essentially different so that complete 
cancellation cannot be hoped for, but a 
good approximation is possible. Simple 
lenses having little glass absorption will 
need less color compensation from the 
coatings than the more complex lenses. 

The complete color specification for a 
lens is given by its spectrophotometric 
curve as shown in Fig. 2. However, a 
single quantity would be convenient to 
use in expressing the varying degrees of 



192 



September 1952 Journal of the SMPTE Vol. 59 






0.20 



0.10 




400 500 600 700 

Wavelength in m/i 

Fig. 2. Spectral transmittance of coated lenses. 



color. It was decided that since we are 
dealing with more or less similar curves 
the difference in characteristics at two 
points of the spectrum would suffice to 
specify the color. From the standpoint 
of measurement accuracy, wavelengths 
should be chosen to give as large a den- 
sity difference as possible. On the other 
hand the limits of sensitivity of color 
films are a consideration. As a com- 
promise 400 and 700 imt were chosen. 
Since transmittance densities are addi- 
tive we shall speak of the color contribu- 
tion in terms of the transmittance density 
difference at 400 and 700 mju. That is, 
Z) 4 oo Z> 7 oo equals the color contribution. 

Having defined this quantity it will be 
convenient to evaluate the two sources of 
color in terms of this quantity. To this 
end we have defined a term known as 
"color index" for a description of the 
color of a piece of glass. 

If t is the glass thickness in millimeters, 



Color Index = 



~ Aoo 



The glasses most free of color have 
values from to 0.0005. The worst 
glasses for color have indices of 0.0300. 
When using color index as a manufac- 
turing tolerance it has been convenient to 
multiply by a factor of 10 4 to give integral 
values 0-300. 

To compute the glass contribution we 
have merely to multiply the lens thick- 
nesses in millimeters by the color index 
of the glass from which the lenses were 
made. The use of densities instead of 
per cent transmittance permits adding 
the values from each lens element. This 
gives us a simple method of determining 
quantitatively the effect of the glass 
absorption, and now we turn to the coat- 
ing problem. 

The color arising from the film coating 
is a function of three variables the 
index of the glass, the number of coated 
surfaces, and the thickness of the coated 
film. The first two are fixed in the de- 
sign of a lens so that we have only the 
last variable left for control. The trans- 



Philip T. Scharf: Transmission Color in Lenses 



193 



mittance through a single coated surface 
may be plotted in terms of transmittance 
density versus wavelength for varying 
film thicknesses. From these curves we 
can tabulate our density difference 
Z) 4 oo D-iQQ for each of several film thick- 
nesses. If we do this for glass indices 
from 1.50 to 1.90, we find that for a given 
film thickness the color contribution 
jD 40 o AGO plotted against glass index 
gives very nearly a linear relation. This 
provides us with an important simplifica- 
tion, for, if we have a lens consisting of 
glasses of differing indices, rather than 
compute the effect for each index we can 
use a "weighted index" for the lens as a 
whole. This "weighted index" is de- 
termined by using for each lens element 
its refractive index times zero, one or 
two, depending upon the number of its 
coated surfaces. These weighted values 
are added together for the entire lens 
and divided by the sum of the weight- 
ings, that is, the total number of coated 
surfaces. We now use a table having 
as entries the film thickness and the 
weighted index. The body of the table 
consists of the color contributions from 
the coated glass surface. We have found 
it convenient to have a table for four, 
six and eight coated surfaces. The dis- 
persion of glass has been taken into ac- 
count in setting up the tables, although 
this is a secondary effect. 

The color contribution arising from 
glass absorption is always a positive 
quantity, i.e., the Z>4oo Aoo is always 
greater than zero since the glass trans- 
mittance density in the blue region is 
greater than in the red. The contribu- 
tion from the coating, however, takes on 
negative values as well as positive values 
and this is what enables us to control the 
transmission color of the lens. A coating 
having its minimum reflection at about 
500 mfj. has a zero value for the term 
Z>40o D 7 QQ regardless of glass index. 



Thinner coatings have negative values, 
thicker ones positive values. There is of 
course a limited amount of control 
offered by the coating; the higher the 
glass indices and the more coated sur- 
faces, the greater the control. For ex- 
ample: a lens having a weighted index 
of 1.70 and eight coated surfaces can 
have a negative color contribution of as 
much as 0.11 while the maximum nega- 
tive contribution from a lens having four 
coated surfaces and a weighted index of 
1.55 is 0.03. 

It is now a simple matter to determine 
the combined effect of glass and coating 
on the transmission color of a lens. But 
we are still without a limiting value for 
this color. It was felt for the most 
critical lenses, interchangeable cine 
lenses, the departure from neutrality 
should not exceed the amount introduced 
by the lightest filter that may be used. 
In the Kodak Wratten series of Light 
Balancing Filters the lightest is the No. 81 . 
It has a value for Z) 4 oo -Dyoo of 0.08. 
It was found that for the simplest cine 
lenses 0.02 represented the minimum 
color contribution. This range 0.02 to 
0.08 was therefore taken as a reasonable 
range of color contribution values for 
cine lenses. Other camera lenses being 
less critical for color could have the 
range 0.0 to 0.10. To avoid any possi- 
bility of the spectral curves becoming too 
highly inflected between 400 and 700 
rm, it is suggested that the expression 
Z) 70 o Aninimum have a maximum value 
of 0.04, that is, the density at 700 m/i 
must be within 0.04 of the minimum 
density wherever it is. 

There will of course be camera lenses 
which cannot be made to meet these 
color specifications. Large aerial lenses 
are examples, but in such cases we do not 
ordinarily have rigid requirements for 
neutral transmission. 



194 



September 1952 Journal of the SMPTE Vol. 59 



Cameo Film Production Technique 



By CHARLES F. HOBAN and JAMES A. MOSES 



Educational and psychological principles applied by the Signal Corps in 
experimental film designed to increase training effectiveness and to cut time 
and cost of production are presented. Also described are story treatment, 
studio techniques, and preproduction analysis and planning that are involved 
in these productions. Results are reported of the evaluation study of film 
effectiveness and audience reaction to scenario treatment. 



N 



ONTHEATRICAL film producers are 
under increasing pressure to do two 
things which appear contradictory and 
irreconcilable. There is the demand 
that training, information and public- 
relations films be produced more rapidly 
and more economically. At the same 
time, there is a demand that the effec- 
tiveness of films be increased. Under 
conventional production procedures, 
films cost too much and take too long to 
produce. When produced, films fre- 
quently do not accomplish their purpose 
as effectively as sponsors hope and have a 
right to expect. To film producers who 
equate "film quality" with film effec- 
tiveness, it seems impossible to make 
better films and, at the same time, reduce 
the time and cost of production. 

In this paper we will describe some 
applications of educational and psycho- 
logical principles of film influence to 

Presented on April 22, 1952, at the Soci- 
ety's Convention at Chicago, 111., by Lt. 
Col. Charles F. Hoban and James A. 
Moses, Army Pictorial Service Div., Of- 
fice of the Chief Signal Officer, Dept. of 
the Army, Washington 25, B.C. 



story treatment and studio methods be- 
ing developed by the Signal Corps to 
improve training effectiveness and reduce 
time and cost of production. Use of 
these procedures will be illustrated in the 
experimentally produced Army training 
film, TF 11-1752 How to Operate the 
Army 16mm Sound Projector Set. There is 
some reason to believe that the basic 
educational principles applied to the film 
on operation of the projector set are not 
necessarily limited in application to this 
particular film or to training films of the 
"nuts and bolts" type. However, we 
are not concerned with a specific tech- 
nique used in the experiment. It just 
happened that the particular production 
technique fitted the subject and accom- 
plished the desired results. Under no 
circumstances should the production 
technique used in this film be construed 
as a "blueprint" for film productions in 
general. 

Two sources of inspiration for im- 
proved film production procedures and 
techniques are currently available. For 
one thing, the possibility of low-cost, rapid 
program production has been explored 
extensively by commercial television and 



September 1952 Journal of the SMPTE Vol. 59 



195 



by the Navy's Special Devices Center at 
Port Washington, N.Y. The affinity of 
television to radio, by way of establish- 
ment of television studios and networks 
in association with radio studios and net- 
works, brought into television a group of 
artists, craftsmen and technicians not too 
familiar with motion picture production 
and motion picture studio practice. 
Partly because of studio and small-screen 
limitations, and partly because of fresh 
talent in the television industry, tele- 
vision has changed the format of video 
presentation and revived many tech- 
niques successfully used in the past in 
military training and other nontheatrical 
films. 

The second influence on film production 
methods and techniques, particularly in 
training and informational films, is the 
growing body of research data on factors 
which increase the instructional effec- 



tiveness of motion pictures. On the 
whole, this research has tended to verify 
and emphasize the applicability to mo- 
tion pictures of well-known instructional 
procedures, and to demonstrate that the 
training and informational effectiveness 
of films is measurably increased when 
instructional procedures are incorporated 
into film production. 

This emphasis on instructional tech- 
niques in training and informational films 
is almost as unwelcome to the profes- 
sional film producer as is the emphasis 
of the television producer on production 
shortcuts and simplified background and 
sets. Teachers are, as J. E. Morpurgo 
says in The Impact of America on European 
Culture, "the depressed class in America's 
predominantly commercial society." 
Instruction techniques are associated 
with teachers. Submergence of teachers 
in the American value system submerges 




Fig. 1. ". . . occasionally Jim steps out of his role, and for a moment, is the 
master of both the machine and of the practical aspects of the theory." 



196 



September 1952 Journal of the SMPTE Vol. 59 



the prestige of instructional techniques 
identified with teachers. However, the 
relationship of scientific research in 
nuclear physics to the engineering de- 
velopment of the atomic bomb had the 
indirect effect of raising the status of 
scientific research in the American value 
system. The soft-spoken professor, with 
umbrella and academic detachment, 
achieved sudden and unprecedented 
status. Consequently, academic re- 
search on motion picture influences and 
on factors which increase effectiveness of 
motion pictures in training and informa- 
tion has today achieved a prestige and a 
measure of governmental support com- 
pletely unknown before World War II. 

The net effect of instructional film 
research has been the renewed emphasis 
in nontheatrical film production on 
application of these techniques. Where 



teachers failed to influence producers of 
teaching films the research technician, 
working under controlled laboratory 
conditions and employing such terms as 
"audience participation" to describe 
what was formerly referred to as "re- 
citing" and "classroom drill," has suc- 
ceeded in raising by halo effect the 
status of instructional techniques as a 
recognized element of training and in- 
formational films. 

Our discussion of the relationship of 
these two factors, i.e., (1) instructional 
film research findings and (2) television 
emphasis on rapid, low-cost program- 
ming, to current trends and innovations 
in training and informational film pro- 
duction will be organized around three 
topics: first, story treatment; second, 
studio methods; and third, preproduction 
analysis and planning. 



I. Story Treatment 



There are several things about the 
story treatment of the Signal Corps' 
experimental film, TF 11-1752 How to 
Operate the Army 76mm Sound Projector Set., 
that were intended to serve the dual pur- 
pose of cutting production time and cost 
and increasing training effectiveness of 
the film. First, we incorporated into 
this film a number of instructional princi- 
ples which have firm foundation in cur- 
rent theory of educational and social 
psychology. One such principle, long 
stressed by William A. Brownell, dis- 
tinguished educational psychologist, is 
that instructional materials, to be in- 
structionally effective, must be produced 
so as to reflect process of learning, not sim- 
ply the product of learning. 

Following this dictum, story treatment 
of TF 11-1752 was developed so as to 
teach operation of the projector in the 
way trainees actually behave in learning 
this operation, and not exclusively to 
demonstrate the way projectionists be- 
have after they have learned and prac- 
ticed their lessons. 

To do this, two characters were cre- 
ated: Jim, the trainee; and the off- 



stage voice of the expert. This provided 
two models for the audience: the one 
who could be imitated immediately, and 
the other who represented a model of 
future performance. The technique of 
the off-stage voice had been used previ- 
ously by the Signal Corps in production 
at the end of World War II of a series of 
films on map reading. 

Jim, the trainee, was carefully de- 
veloped in the scenario and carefully 
cast. His ability to handle the projector 
set, clean it and operate it is established 
on a level slightly above that of the com- 
plete novice, but somewhat below that of 
the expert. Occasionally, in the pic- 
ture, Jim steps out of his role and for a 
moment is master both of the machine 
and of the practical aspects of the theory. 
But, characteristically, Jim is the pleas- 
antly alert and occasionally forgetful 
American young man, temporarily in 
Army uniform, who prides himself on his 
ability to master machines and compli- 
cated equipment. 

Jim is objectified on the screen. He 
can be seen and heard and his perform- 
ance can be carefully observed and easily 



Hoban and Moses: Cameo Production Technique 



197 



evaluated by the trainee audience. The 
off-stage voice, on the other hand, is 
transparent. The audience is free to 
project physical characteristics, rank, 
occupation and status into the off-stage 
voice. His competence as an expert, 
however, is thoroughly established in the 
film that, and no more. Preliminary 
analysis of audience reaction to this film, 
under actual classroom conditions, indi- 
cates that the off-stage voice is dominant 
in the film, and that the audience pro- 
jects more desirable qualities into this 
unseen character than to Jim, who ap- 
pears in almost every scene. 

In developing the story treatment into 
which the characters of the trainee and 
the experts are interwoven, two addi- 
tional principles of instruction were 
introduced. To be effective as a teach- 
ing device, it was essential that the film 
have a psychological organization rather 
than a purely logical organization. Ex- 
perience in projectionist training indi- 
cates an impatience on the part of the 
trainee with postponement of practice in 
the actual threading and operating of 
the projector, and lack of readiness for 
instruction in assembly, inspection, pre- 
ventive maintenance, nomenclature and 
disassembly, until the point of operation 
has been passed. Logical organization 
of the treatment of the subject, based 
upon identification and explanation of 
component parts and on time sequence 
of operations, would, it was assumed, go 
contrary to the readiness of the audience 
for instruction. The law of readiness is 
an old concept in educational psychol- 
ogy, and a valid one. Deliberately to 
proceed in film instruction contrary to 
this law would, at least theoretically, re- 
duce the teaching effectiveness of the 
film. The problem of logical versus 
psychological organization of subject 
presentation was solved, in part, by 
backing into the subject. This was done 
by opening the film with Jim, the 
trainee, preparing to place the full reel of 
film on the feed arm, and to thread and 
operate the projector. 



Another instructional principle intro- 
duced into the story treatment was that 
of interrupted action. An audience has a 
tendency, amounting to a compulsion, 
to complete an action once the action has 
been started. Interruption and suspen- 
sion of action before completion, or 
omission of a part of a film obviously 
included in the original version, tends to 
create a tension in the audience which 
can be satisfactorily discharged by com- 
pletion of the initiated action or exhibi- 
tion of the omitted part. This tendency 
is well documented, and is closely related 
to the well-known psychological phe- 
nomenon of closure. The problem in 
film production is to apply the principle 
of interrupted action to story treatment 
so that it operates to increase the in- 
volvement of the audience in the subject 
of the film and thereby increase learning 
and retention. 

The off-stage voice was used to accom- 
plish this intent. Actually, the off-stage 
voice served several purposes. As 
already indicated, it constituted a trans- 
parent model of expert knowledge and 
competence in operation of the projector 
set. Second, the off-stage voice, by 
remaining off-stage, permitted individual 
visual concentration on Jim, the trainee, 
and on the projector set. Third, the 
off-stage voice was used as a device, a 
gimmick, if you will, for repetition and 
emphasis of the important teaching 
points of the film. Finally, the off-stage 
voice was used as a device for inter- 
rupting Jim's progress in threading and 
operating the projector in order to insure 
and insist on prethreading and pre- 
operating checks, cleaning and projector 
adjustment. Preliminary analysis of 
field evaluations of this film, to which 
reference has already been made, indi- 
cates that, while the interruptions may 
have annoyed the audience, the teaching 
effectiveness of the sequences accom- 
panying the interruptions appears to 
have been strengthened. 

Two other characters were used 



198 



September 1952 Journal of the SMPTE Vol. 59 



one, another off-stage voice somewhere 
in the gallery; the other, a clearly visual 
WAG. The Voice-from-the-Gallery 
had a twofold purpose. The less im- 
portant of these was that of a gimmick 
used to sustain interest in the film by the 
introduction of contrast and disharmony. 
Generally speaking, nontheatrical film 
producers act on the premise that it is 
impossible to maintain audience interest 
for thirty-odd minutes in a film dealing 
with the operation and care of a piece of 
technical equipment such as the JAN 
projector set. This premise sometimes 
approximates an article of credo in the 
trade. Use of the Voice-from-the- 
Gallery was a nod to this credo and a 
form of insurance against possible waning 
interest in the audience. The more im- 
portant reason for use of the Voice-from- 
the-Gallery was to simulate audience 
participation in the demonstration and 



explanation of the projector set. The 
Voice-from-the-Gallery raised the kinds 
of questions which, it was anticipated, 
would exist in the mind of the audience. 
In this way, the Voice-from-the-Gallery 
' acted as audience protagonist during the 
film showing. It was conceived as 
somewhat of a character and no attempt 
was made to disguise this conception in 
the film. Approximately 10% of the 
projectionist trainees resent this charac- 
ter, but it is generally admitted that he 
raised questions pertinent to the subject 
of the film. 

The Voice-from-the-Gallery was also 
used as a device for emphasizing two 
facts which needed to be established for 
the audience: (1) the existence, im- 
portance and usefulness of mimeographed 
directions on operation of the projector; 
and (2) the concept of the film as a 
specific training aid, rather than a corn- 




Fig. 2. ". . .the off-stage voice was used as a device for interrupting Jim's prog- 
ress and for repetition and emphasis of the important teaching points of the film. 



Hoban and Moses: Cameo Production Technique 



199 



plete course of instruction on operation 
of the JAN projector set. 

In shooting the picture, the Voice- 
from-the-Gallery was recorded during 
the noon-hour lull of one day of produc- 
tion. The off-stage voice, however, was. 
recorded in dialogue on the set simul- 
taneous with the live action. This pro- 
cedure was intended to increase the spon- 
taneity and realism of the running dia- 
logue between Jim and his off-stage men- 
tor. 

The fourth character in the film was 
the WAG. The purpose of the WAG 
sequence was to poke fun at the com- 
plaints about the weight of the complete 
projector set. The facts are that the 
JAN projection equipment is heavy and 
consists of three pieces. There is no 
point in pretending in the film that these 
facts do not exist. The alternative is to 
attempt to reduce possible adverse reac- 
tion to these factors. Contrary to some 
expressed audience reaction, the WAG is 
not a lady wrestler. Her facility in 
carrying the projector and amplifier was 
actually a facility in carrying an empty 
projector and amplifier case supplied by 
the prop department. 

The WAG sequence is pure corn. 
There is no objection to corn in an in- 
structional film if it is useful as a means of 
accomplishing one of the purposes for 
which the film is made. The valid 
objection to the use of corn in a training 
or informational film is the use of corn 
for its own sake. In general, the audi- 
ence of projectionist trainees sees the 
WAG as a device for combating gripes or 
simply as a device to leave the audience 
in a good mood. 

Several other instructional techniques, 
the importance of which has been indi- 
cated in film research, were incorporated 
into the film. The use of repetition has 
previously been indicated. The thread- 
ing of the projector was shown three 
times. The use of the lens lever was re- 
peatedly demonstrated. Care in re- 
moval of the aperture and pressure 
plates was repeated. Slow rate of de- 



velopment was a must in acting, shooting 
and editing. The instruction in the 
film moves at a rate geared to a learning 
audience. Except in a few instances, 
subjective camera angle was employed, and 
extreme close-ups were extensively used. 
Repetition, slow rate of development and 
subjective camera angle have been 
shown in experimental film research to 
measurably improve instructional effec- 
tiveness of films demonstrating manual 
operations. 

Basic to story treatment and scenario 
of this film was the concept of conflict and 
the importance of conflict in the learning 
process. If there are no obstacles to be 
overcome, or no need to overcome 
obstacles, there is little or no need to 
learn. Hence the introduction of the 
concept of conflict into the story treat- 
ment. Throughout the film, there is the 
continuing problem of whether Jim will 
triumph over the machine or the ma- 
chine over Jim. In counterpoint, is the 
implicit and friendly conflict between 
Jim and the off-stage voice. These 
sorts of conflict prevail and are accepted 
as challenges in the American culture. 

The general principle of story treat- 
ment of instructional films underlying 
the Signal Corps' use of the conflict con- 
cept in the experimental film is the de- 
sirability, if not actual necessity, of taking 
into account those characteristics of the 
culture of a society which are dominant in 
social behavior, and to incorporate these 
cultural characteristics into films in 
order to increase the audience acceptance 
of the informational and instructional 
content of the film. Perhaps more than 
we realize, these cultural characteristics 
may be extremely important to the 
dynamics of film influence and film real- 
ism than elaborate backgrounds, estab- 
lishing sequences and the polished per- 
fection of studio props. 

Throughout the story treatment and 
scenario preparation of TF 11-1752 was 
the psychologically respectable but fre- 
quently ignored idea that, since instruc- 
tion has to do with learning, and learning 






200 



September 1952 Journal of the SMPTE Vol. 59 



is done by the learner, the subject must be 
approached from the point of view of the 
learner. Training, informational and 
propaganda films are often produced 
from exactly the opposite point of view. 



They consist of the expert presentation 
of a subject by an expert on the subject 
on the assumption that film is some sort 
of magic medium of transmission of wis- 
dom from the wise to the ignorant. 



II. Studio Techniques 



The term Cameo Technique is used 
here to describe some of the studio tech- 
niques applied to the experimental film, 
TF 11-1752, in order (1) to cut time and 
cost of production and (2) to increase 
teaching effectiveness of the film. As 
we all know, a cameo is a stone on which 
a character is carved in relief. The TV 
Cameo Theater is so named, presum- 
ably, because of the exclusive employ- 
ment of the cameo technique in video 
presentation. 

This technique consists of the omission 
of background in the studio set, the in- 



clusion of only essential foreground ob- 
jects and characters, and the spot lighting 
of these objects and character action. 
Picturewise, these are suspended in an 
enveloping blackness. Nothing is visible 
to distract attention from the essential 
characters and objects around which the 
story treatment is built. Use of this 
technique served the twin purpose of 
simplifying studio production and of in- 
creasing audience concentration on the 
essentials of the subject. 

In the production of the Army's film 
How to Operate the Army's 76mm Sound 
Projector Set, only one set was used, the 




Fig. 3. "In the production of the film on How to Operate the Army's 16mm 
Sound Projector only one set was used." 



Hoban and Moses: Cameo Production Technique 



201 



walls of which were draped with gray 
curtains, hanging in folds and following 
the L-shaped pattern of the set. With 
this L-shaped set, draped in such a man- 
ner, only the screen, the speaker, the 
projector and amplifier, the table for the 
spare parts, and the actor required 
lighting, and these by spots. The lack 
of background permitted easy movement 
of prop equipments for front, back and 
side views; long shots, close-ups, reversal 
shots, and relative constancy of camera 
position and spot-light location and 
regulation. The draped L-set (1) facili- 
tated the rapid shooting of the picture 
and (2) reduced the cost of set construc- 
tion and lowered personnel requirements 
for electricians and grips. 

The general principle illustrated by 
the Cameo Technique as used in the 
Army's TF 11-1752, is that foreground, 
not background, is the focus of action and 
attention in a motion picture. The context 
essential to perception of meaning is 
shifted from more or less accidental and 
purely situational settings, which vary in 
any given operation, to a simple presen- 
tation of crucial cues, consisting of mean- 
ingful and irreducible wholes in which 
elements, parts and fragments are em- 
bedded. 

Motion pictures have traditionally 
been based de facto on a theory of fidelity 
of representation. It has been assumed 
that an audience can perceive the full 
meaning of a picture only when a full 
clutter of all visual background is faith- 
fully photographed and reproduced on 
the screen. Among other things, intel- 



lectual activity consists of abstracting 
essential meanings from the clutter of 
context and situation. Where the pur- 
pose of a film is to facilitate this intellec- 
tual process of abstracting and analyzing 
essential meanings and essential opera- 
tions out of their contextual clutter, it 
seems reasonable that the principle under- 
lying the Cameo Technique actually 
facilitates the desired audience response. 
The usual studio treatment, based on an 
exaggerated fidelity-of-representation 
theory, may interfere with or at least not 
substantially contribute to this end. 

Another aspect of studio and story 
treatment of TF 1 1-1752 which relates to 
the ideas back of the Cameo Technique 
is elimination of the conventional build- 
up in the film of the introduction to the 
subject. For the most part, elaborate 
establishment of situations in order to 
obtain audience rapport is unnecessary, 
costly and time consuming for an audi- 
ence reasonably sophisticated in the 
subject. 

In TF 11-1752, the film opened with 
the projector set assembled and the pro- 
jectionist preparing to thread the film 
through the projector. The film is 
intended for use in projectionist training 
programs for military trainees, all of 
whom have completed basic training and 
presumably are aware that military 
training is essential to successful military 
operations and to personal survival, and 
that training films are good training aids; 
also, that the effectiveness of any film 
presentation is greatly enhanced by good 
projection of the film. 



III. Preproduction Analysis and Planning 



It is apparent that story, scenario and 
studio treatment of the Army's training 
film, TF 11-1752, involved both a great 
deal of preproduction analysis and plan- 
ning, and a working familiarity with 
theory and research on the dynamics of 
motion picture influence. If time and 
cost of production were to be cut, in- 
creased emphasis on preproduction anal- 



ysis and planning was required. If the 
effectiveness as a training and informa- 
tional film was to be increased, then the 
principles of effective instruction had to 
be incorporated. 

Preproduction analysis was needed in 
three areas: (1) the audience, (2) the 
objectives of the film, and (3) the situa- 
tion of film use. In every motion pic- 



202 



September 1952 Journal of the SMPTE Vol. 59 



ture situation, there are always two, not 
just one, important parts: the audience 
and the film. We started with the 
audience. 

There were two things which we were 
required to know about the audience be- 
fore we could effectively plan the film to 
instruct, inform or otherwise influence 
the audience: First, who was the in- 
tended audience and what was it like? 
Second, what did the prospective audi- 
ence already know about the subject? 

The anticipated audiences of TF 11- 
1752 consisted of military trainees 
a cross section of American youth. They 
are motivated by the typical American 
drive to "get the job over with." Army 
service is accepted as something neces- 
sary to get the job over with, and Army 
training is part of the job. Eight out of 
ten of the draftees in today's Army have 
received some high school education. 
Fifty-five percent have graduated from 
high school. Twenty-two percent have 
attended college. For the most part, 
these trainees have learned to learn. 

Since these military trainees grew up 
in industrial America and have had 
considerable formal education in the 
American school system, we assumed 
that they were already familiar with the 
following: 

1. Electrical cords, plugs and outlets, 
such as used in homes, schools, etc., as 
conductors of electricity. 

2. Flow of electricity through circuits, 
controlled by switches. 

3. Sound volume controls such as 
found in radios, phonographs, televisions, 
and other audio equipment. 

4. Electrical motors, such as found in 
vacuum cleaners, washing machines, 
electric fans and mixers, and their func- 
tional responsibility in the supply of 
mechanical power. 

5. Incandescent lamps, common items 
in homes, schools, businesses, etc., as a 
source of light. 

6. Sound amplifying systems, such as 
used in all radios, televisions, phono- 
graphs, etc. 



The objective of the film was to in- 
struct the intended audiences, described 
in the preceding paragraphs, so that they 
would both feel competent to and be 
able to perform the following operations 
on the projector: 

1. Preoperation check of electrical 
connections. 

2. Threading of film through the 
projector. 

3. Preoperation check on sound sys- 
tem. 

4. Prethread cleaning of film path. 

5. Prethread and preprojection focus- 
ing. 

6. Replacement of projection and ex- 
citer lamps, and other operating spares. 

In addition, it was important that, in- 
sofar as possible, the film influence the 
attitude of the trainees toward the pro- 
jector and its care and use. These atti- 
tudes were spelled out, as follows: 

1. The good projectionist uses com- 
mon sense. 

2. While the projector set appears to 
be complicated, the mastery of the 
equipment is not difficult if recom- 
mended procedures are observed. 

3. Careful checking and cleaning of 
the equipment should be performed be- 
fore each use. 

4. The equipment is not too heavy for 
men to carry. 

5. There is more to learn about the 
equipment than is shown in the film. 

The film was produced for use in 
organized Army projectionist courses. 
In all such courses, ample provision is 
made for classroom practice on the 
projector set, under the supervision and 
guidance of the instructor. 

In the instructional procedure, the 
training film, TF 11-1752, will be shown 
immediately before the students are per- 
mitted to handle the projection equip- 
ment. A second showing of the film 
will be scheduled at the end of the course, 
just prior to the period for the qualifying 
examinations. Another Army training 
film, TF 11-1574 Technique of Good Pro- 



Hoban and Moses: Cameo Production Technique 



203 



jection, is already being used in the course 
and will continue in the schedule, to 
show the importance of good projection 
in the classroom and how this is accom- 
plished. 

With such advanced knowledge of the 
situation of use, the instruction and prac- 
tice to follow the showing of the film, and 
the availability of a sister film covering 
projection techniques, it was possible to 
limit the content of the film to the essen- 
tials of prepractice instruction. Fur- 
thermore, the fact that the audience was 
enrolled in a projectionist training course 
made it possible to eliminate the "estab- 
lishing sequences" and to open directly 
on the subject. Assembly and disassem- 
bly of the equipments were omitted 
from the film, since these operations are 
taught in the practice phase, working 
directly with the equipment. 



Considerable experience gained from 
associating with projectionists and teach- 
ing projectionist training courses, and 
considerable thinking on the objectives 
of the film in terms of audience perform- 
ance and audience attitudes toward the 
Army projector set, went into the first 
treatment of the story outline, prior to 
conferences with the writer regarding 
scenario preparation. The nature of the 
audience, the assumptions on existing 
knowledge of the audience, the objectives 
of the film in terms of performance and 
attitudes, and the situation of film use 
were spelled out in advance of the 
scenario-planning phase. 

We encountered no difficulty, no mis- 
understandings, no obstruction and no 
opposition anywhere along the line, once 
performance specifications were clearly 
set forth for all to examine. 



204 



September 1952 Journal of the SMPTE Vol. 59 



Auditorium Specifically Designed 
for Technical Meetings 

By D. MAX BEARD and A. M. ERICKSON 



The Naval Ordnance Laboratory, White Oak, Mel., is not only a research 
and development center for ordnance material, but it has also become a 
center for the dissemination of scientific information. Technical meetings 
and symposia of international fame have been held in the auditorium, specifi- 
cally designed for such meetings, seating 550, with optimum acoustics. 
Included are a console for control of 21 microphones, telephone communica- 
tion with the moderator, and controlled levels to sound recording facilities. 
The projectionist has direct contact with the speaker, the console, the thyra- 
tron-controlled overhead lights, and preset stage lighting. Complete audio- 
visual aids are available. 



JL HE NAVAL ORDNANCE LABORATORY 
has the primary objective of the de- 
velopment of new and better ordnance 
for the United States Navy's Bureau of 
Ordnance, and is destined to become one 
of the outstanding research centers of 
the nation. It must be realized not 
only that it is essential to equip this 
research activity with the most modern 
and complete facilities, but also the 
laboratory must be equally well equipped 
with a staff of fully informed scientific 
personnel. 

It was recognized late in World War 
II, while planning for the new laboratory 
at White Oak, Md., that every effort 
should be expended to maintain ade- 
quately trained technical personnel to 



Presented on April 22, 1952, at the Society's 
Convention at Chicago, 111., by D. Max 
Beard, Naval Ordnance Laboratory, Silver 
Spring, Md. 



make and keep this laboratory a note- 
worthy research center whether at 
war or in peacetime. As a result of 
these efforts, this laboratory has, in 
addition, become an intellectual center 
for the dissemination of scientific in- 
formation. It is for this phase of 
endeavor that its auditorium was planned 
and is dedicated. 

The lot of the scientist speaker is not 
always an easy one. His subject is 
usually one that must be closely followed 
and have a minimum of interruptions. 
He must have full assurance that he can 
be heard or that his visual aids are 
clearly discernible to the entire audience. 
Of equal importance is the comfort of 
his audience, who must expend a con- 
siderable amount of mental effort to 
keep up with the subject, and certainly 
cannot do so if there is an accumulation 
of distractions such as hard seats, foul 



September 1952 Journal of the SMPTE Vol. 59 



205 




Fig. 1. The NOL auditorium showing lectern in its normal position, 
with microphones in place for audience participation. Questions may 
also be written down and handed to assistants at the aisle mikes. 




Fig. 2. Visual aids, such as opaque projection, Viewgraph, charts, blackboard, 
pointers, etc., are readily available to the speaker even when presenting his talk 
to a small group from out in front of the stage. Microphones are strategically 
placed to give the lecturer as much freedom as possible, while at other times 
lapel microphones are used. Floor outlets would be preferred to the present 
outlets along the front of the stage. 



206 



September 1952 Journal of the SMPTE Vol. 59 




Fig. 3. Rear of the auditorium showing the location of the control console, 
the contour of the rear wall and the projection-room parts. 



air, disturbing lights and poor audi- 
torium acoustics. The NOL audi- 
torium is designed to put both the 
speaker and his audience at ease. 

The major points considered in the 
design of this auditorium were: (1) 
audience comfort; (2) intelligibility; 
(3) availability of visual aids; (4) con- 
trolled levels of illumination and sound; 
and (5) flexibility of the overall system. 
The facilities for these results are herein 
described. 

Several members of this Society gave 
excellent advice, and were instrumental 
in the final design and engineering of the 
auditorium. Since most contacts were 
made through the Society, the writers 
would like to express their appreciation 
to the Society for this assistance. How- 
ever, special mention is made of the 
work of Al Ward and John Volkmann 
of the Radio Corporation of America 
who were responsible for the acoustics 
and sound system engineering, and J. 
E. Currie of the National Theatre 
Supply Company who assisted in the 
layout of the projection sound system on 



the stage and in the projection booth. 
The Photographic Division of this 
laboratory is responsible for the further 
tailoring of the installation in its present 
exacting requirements and its operation. 
The auditorium, seating 550, has a 
reverberation time of approximately 
0.75 sec, which is slightly less than that 
of a comparable-size (200,000-cu ft) 
motion picture theater (see Figs. 1, 2 
and 3). To achieve these desirable 
acoustics, and to keep within the struc- 
tural limitations of the building, the 
interior was altered to include poly- 
cylindrical sections, sloping floors and 
a serrated rear wall. Absorbing ma- 
terial was selected and placed to give 
optimum acoustics, with side walls 
surfaced with acoustic plaster, the 
ceiling of standard plaster, and over- 
stuffed theater seats. An on-the-stage 
lecturer with good speaking quality 
may be easily heard at the rear of the 
auditorium without the aid of sound 
reinforcing. These acoustic properties 
are not only desirable for lectures, but 
are ideal for recording purposes. 



Beard and Erickson: Auditorium for Technical Meetings 



207 



The stage is similar to small theater 
installations with several added features 
such as: (1) a one-ton hoist for moving 
equipment for demonstrations; (2) alter- 
nating- and direct-current power, signal- 
ing and microphone outlets available 
at various points; (3) microphones 
behind the projection screen, permitting 
the speaker to have complete freedom 
from the lectern; (4) removable pro- 
jection screen and motion picture 
speaker systems; and (5) sound rein- 
forcing speakers overhead and slightly 
in front of the stage in the proscenium 
arch. 

The projection booth, shown in Fig. 4, 
is equipped to handle 16mm and 35mm 
motion pictures, and 2 in. X 2 in. 
standard and continental lantern slides. 

The standard-size dissolving slide 
projector was altered to accommodate 
1000-w incandescent projection lamps, 
with special blowers and heat-resistant 
glass to permit prolonged projection of 



negative lantern slides. This is quite 
important since some scientists may 
discuss one lantern slide for as long as 
ten minutes. House-light dimmer and 
curtain controls are located in the booth 
at each of the viewing ports. The stage 
light control is centrally located. 

Slide-changer buzzer, auditorium 
monitor, intercommunication and tele- 
phone communication are readily ac- 
cessible to most of the normal operating 
positions. Accurate focusing of all pro- 
jectors is accomplished by means of a 
seven-power monocular sight that is 
movable to each viewing port. In 
addition to the monitor speakers on the 
two sound channels, a sound-level 
meter is bridged across the stage speaker 
bus and provides a positive indication 
of sound level being delivered to the 
auditorium. 

The auditorium sound reinforcing 
system (Fig. 5) is designed to be con- 
trolled from a mixing console (Fig. 6) 




Fig. 4. The projectionist utilizes a monocular sight to get accurate focus 
on all projection from the booth. The dissolving slide projector controls 
and modified heat-dissipating system may be noted on the projector at 
the right of the operator. 



208 



September 1952 Journal of the SMPTE Vol. 59 



2 PROJECTION SPEAKER LINES 
STAGE BOOTH TELEPHONE 



AUDITORIUM LIGHT REMOTE CONTROL 
FRONT CURTAIN REMOTE CONTROL 
SCREEN CURTAIN REMOTE CONTROL 
BOOTH MONITOR 
SLIDE BUZZER 




6 LINES TO REC RM 

2 SPARE LINES 

OUTSIDE TELEPHONE 

12 LINES TO P A RM 

2 LINES TO CAFETERIA 

2 LINES TO LOUNGE 

PHONE TO CENTRAL REC 

INT COM TO CENTRAL REC 



9 AISLE MICROPHONE LINES 



Fig. 5. Schematic of sound and control services. The entire operation for 
limited services may be controlled from the projection booth, utilizing preset 
levels at the control console. 




Fig. 6. The operator of the control console not only has a clear view 
of any activity in the auditorium, but has complete control of all sound 
facilities by means of switches, attenuators for sound reinforcing and 
recording. 



Beard and Erickson: Auditorium for Technical Meetings 



209 



at the rear of the audiiorium. This 
console contains 21 microphone pre- 
amplifiers and 2 line amplifiers. As 
many as 12 circuits can be mixed at 
one time with provisions of level adjust- 
ments on each circuit. One of the two 
output circuits drives the sound re- 
inforcing amplifiers and the other may 
be patched to the sound recording 
facilities, or to other areas on the base 
at NOL. Communication facilities are 
available with the symposium modera- 
tor, projection booth, backstage and the 
recording room. The outside telephone 
is provided with a light signal rather 
than a bell so that incoming calls do 
not disturb the lecturers. 

This control console mixer system is 
particularly adapted to audience par- 
ticipation. The operator with his com- 
mand view of all microphones on stage 
and in the aisles can switch in micro- 
phones or interchange and maintain 
levels as required. The result is excel- 
lent sound reinforcing of all pertinent 
discussions regardless of whether they 
are between the lecturer and a par- 
ticipant from the audience, or among 
two or three members of the audience. 
This flexibility is extremely valuable 
where it is desirable to record every word 
of international symposia. 

The auditorium is utilized in many 
different ways: 

(1) For week-long symposia, nearly 
every facility must be made available 
to include audience participation, all 
projection services, lapel microphones, 
lectern, projectionist working from 
scripts, intercommunication with outside 
activities, and complete sound record- 
ing, which includes all verbal combats 
between members of the audience. 
Performances of this type have not only 
been completely recorded, but tran- 
scribed and eventually published in 
book form. 

(2) Seminars. 

(3) Public-speaking training courses. 

(4) Junior professional training. 

(5) Intra-Defense Department dis- 



cussions. Many interesting situations 
come up that can hardly be avoided. 
Difficulties will probably always arise 
wherein some lecturers fail to have 
their slides in order or properly marked, 
and where they are frequently of such 
a nature that only the speaker himself 
can tell which is the top of the slide, or 
other speakers who in their nervousness 
continually press the buzzer to the pro- 
jectionist indicating a change of slides. 
The projectionist, in his effort to make 
one change per buzz, may run several 
slides ahead. Another problem occurs 
when two audience participants of de- 
cidedly unequal voice levels are at 
microphones on the same console control 
switch. Conflicts of this type have 
been eliminated by repatching; how- 
ever, some problems can hardly be 
corrected by modification of the facilities. 

There are several improvements that 
are highly desirable in an auditorium 
designed for this type of operation. 
Most noticeable among these are the re- 
quirements for panels for the use of 
charts, etc., that may be pushed off 
stage when no longer required; more 
complete facilities in front of the stage 
for small groups; a system of lights on 
lectern (in view of the speaker only) 
controlled by the moderator, to warn 
the speaker he is lecturing beyond his 
allotted time; an improved system of 
microphones for audience participation; 
screen set flush with the rear of the stage; 
acoustic baffles on the air-conditioning 
ducts; a stereophonic sound and pro- 
jection system; acoustic treatment in 
the booth; and possible use of variable- 
focal-length lenses for 2 in. X 2 in. slide 
projection. The magnetic sound track 
on 16mm film will be a boon to the 
functions of this auditorium. 

The auditorium at NOL, although 
originally planned about seven years 
ago, has been kept up to date in most 
respects and has proven most satis- 
factory in nearly every respect for the 
type of performance required of it. Of 
the five major points considered in the 



210 



September 1952 Journal of the SMPTE Vol. 59 



original planning: audience comfort, 
intelligibility, availability of visual aids, 
controlled levels of illumination and 
sound, and flexibility, the one most 
overtaxed has been the last. There 
have never been any regrets that every 
consideration was given to this in the 
early planning, and the extra lines, 
conduits, etc., that were included in the 
original design have made it unnecessary 
to make any major or expensive altera- 
tions to the auditorium. 



Discussion 

George Lewin (Signal Corps Photographic 
Center}: I wonder if ybu've ever given any 
thought to providing a remote-control of 
focus on either your slide projectors or 
your motion picture projectors, so they 
could be controlled, say, either from the 
lectern or by somebody in the audience. 

Max Beard: We have never tried that. 
Does it work pretty well? 

Mr. Lewin: Well we use it to some 
extent in running dailies, because there's 
always a question as to whether the pro- 
jectionist has the same idea about focus 
as the audience. 

Mr. Beard: I wonder if the speaker 
close to a screen could determine the focus 
as accurately as the man from the booth 
with the telescope; 

Mr. Lewin: Well, probably not the per- 
son near the screen, but somebody in the 
audience, that is somebody assigned, of 
course, by the speaker could take care of 
that. 

Mr. Beard: It's of interest to point out 
that very often when you're running film, 
the film goes in and out of focus at times 
for reasons beyond the control of the pro- 
jectionist (he's not always watching it that 
closely). 

Chauncey L. Greene (RKO Orpheum Theater, 
Minneapolis}: I've used the seven-power 
binocular for checking focus as well as 



trying to control it from near the screen. 
My personal experience has been that the 
Navy seven-power binocular critically 
focused beforehand upon a target located 
near the screen is far superior to trying to 
control it from a position near the screen, 
because you have really a more critical 
view of what you are trying to do. I've 
never had much success with a monocular, 
and a poor quality binocular is worse 
than useless, but that 7 X 50 Navy glass 
is probably the world's finest for this 
purpose. True, if you try to operate the 
entire projection establishment single- 
handed, it is not going to receive the 
attention that it deserves either through 
binoculars or without them. Lastly, might 
I express an opinion that this Society 
could render no greater service than to 
mail a reprint of this paper to the Visual 
Education Department of every college 
or institution of learning in this country. 

Mr. Beard: Thank you, Mr. Green. 
There's an additional comment I might 
make. The biggest problem we have, 
when focusing, is the shifting from 3^ in. X 
3J in. to a 3J in. X 4 in. lantern slides. 
The projector we have has different 
positions for these two types of slides, 
which means that every time you project 
the continental slide (3| in. X 3J in.) 
you have to refocus the projector. This 
is a big problem with us, since we fre- 
quently get a mixture of the continental 
and standard slides. 

Chester Beachell (National Film Board of 
Canada}: Have you any facilities in this 
auditorium for providing different screens, 
such as perforated matte, a beaded screen, 
or a silver screen for a Polaroid stereo 
projection? 

Mr. Beard: We use the perforated screen 
for all projection. We have not tried the 
Polaroid system; however, we are quite 
anxious to do so some day. 

Mr. Beachell: It has been my experience 
that a matte screen won't work on Polaroid 
stereo at all. It scrambles the light 
polarity. 



Beard and Erickson: Auditorium for Technical Meetings 



211 






Safety Requirements in Projection 
Rooms and Television Studios 



By SAMUEL R. TODD 



Nitrate film has imposed special requirements on projection-room design for 
many years. The advent of 35mm safety film may change some of these, 
and this possibility is discussed. The increasing use of films, both nitrate 
and safety types, in television studio operations calls for similar precautions, 
and the presence of considerable electronic equipment adds to the normal 
hazards. These hazards and certain others peculiar to live program pres- 
entations are discussed. Safety problems involved in the installation and 
operation of high-voltage television equipment in theaters are outlined. 



PROJECTION ROOMS IN MOTION PICTURE THEATERS 



Since the first "Nickelodeon" opened 
its doors to the public for presentation 
of motion pictures the greatest safety 
hazard, as is well known, has been the 
fire and panic danger inherent in the 
ever-present possibility of accidental 
ignition of the thousands of feet of 
cellulose nitrate film located in the 
projection room. This continuing haz- 
ardous condition over the years has been 
changed recently, to a considerable 
degree, due to the gradual replacement 
of nitrate film by the so-called "safety" 
cellulose acetate film. However, as 
long as 35mm film remains standard 
for the projection of motion pictures in 
theaters, most safety authorities, many 
theater owners, and those theater de- 
signers who are intimately conversant 



Presented on May 3, 1951, at the Society's 
Convention in New York, N.Y., by 
Samuel R. Todd, 4711 Woodlawn Ave., 
Chicago, 111. 



with the numerous details involved in 
the proper design and construction of 
modern projection rooms for maximum 
safety and best operating features, feel 
that any changes in the specifications 
now considered as standard are both 
unwarranted and undesirable. If we 
assume, and it is a fair supposition, that 
a fireproof type of construction for 
theaters will continue to be demanded 
by local governmental authorities, it 
seems hardly possible that nonfireproof 
type of construction for projection rooms 
would be advocated. 

Let us consider, item by item, some 
of the real reasons for the present type 
of enclosure for the projection, sound 
and accessory equipment in the modern 
theater projection room. To isolate 
from the auditorium unavoidable noises, 
such as those due to the operation of 
equipment and due to conversation 
necessary from time to time, a sub- 



212 



September 1952 Journal of the SMPTE Vol. 59 



stantial enclosure is certainly needed. 
The physical strength alone required 
to safely support the weight of the 
necessary equipment, and to allow for 
the additional weight of four or more 
persons who may be in the room at one 
time, calls for the specification of a 
heavy reinforced concrete floor con- 
structed according to the recommenda- 
tions of a qualified structural engineer. 
Also, and for similar reasons, the four 
walls of the room should be designed to 
assure structural security and adequate 
fire protection as well as the necessary 
physical strength required to support 
electrical raceways and heavy equipment 
items which may be mounted on these 
walls. From long experience in pro- 
jection-room design, it seems advisable 
to call for ceilings not less than 9 ft 
above the projection-room floor level, 
and of structurally strong and fireproof 
construction. Costly films, sound and 
projection systems need protection from 
theft and from fire hazards elsewhere in 
the theater as well as vice versa. Solid, 
fireproof enclosures, with approved fire- 
proof doors equipped with trustworthy 
locks, are thus well justified whether or 
not the films used introduce any special 
fire hazards. 

In the event a fire does occur in the 
projection room, it is instantly and im- 
peratively necessary to completely isolate 
the room from the auditorium in order 
to prevent possible audience panic. 
Panics kill far more people than actual 
fires do. Projection and observation 
port openings must be equipped with 
gravity-operated, automatically con- 
trolled, approved steel fire shutters 
actuated by a master control cord and 
by 160 fusible links, located imme- 
diately above and within 6 in. of the 
upper magazine of each projection ma- 
chine. In the event of a projection- 
room fire, it is necessary to exhaust 
promptly all smoke and odors to the 
outside air. This may be accomplished 
by means of an adequate, forced-draft 
ventilating system; this system may also 



serve to exhaust normally the gases and 
carbon ash from carbon-arc lamp 
enclosures. A natural gravity vent, with 
adequate cross-sectional area extending 
through the projection room ceiling 
directly to the outside air, should also 
be provided as protection in case of 
failure of the electricity supply service. 

Consideration should be given to the 
dimensions of the projection room in 
order to provide normal operating safety 
factors for the projectionist. The room 
should be not less than 12 ft between 
front and rear walls, in order to have 
sufficient working and free walking space 
around all equipment. The rewind 
table should be located at the rear wall 
equidistant from the two projectors. 
The space between projectors should 
be sixty in. at the lens centers and there 
should be a clear space from the lens 
centers of 48 in. both to the right of the 
righthand projector and to the left of 
the lefthand projector. A modern de- 
sign for the rewind table includes space 
beneath the table top for locating 
approved-type film containers, sup- 
ported several inches above the floor. 
In order to deliver on the screen the 
high-quality performance expected from 
the projectionist, he must at all times, 
while on duty, be reasonably calm and 
alert both mentally and physically. 
These considerations, as well as those 
of common decency, call for providing 
adequate modern toilet facilities and a 
lavatory with both hot and cold running 
water in well-designed theater projection 
rooms. 

This brief review and discussion of 
present safety requirements in theater 
projection-room construction is intended 
to justify the conclusion that practically 
all of the requirements are in order 
regardless of the type of film used. 
They obviously must not be relaxed 
in any degree so long as there is a 
possibility that even small quantities 
of cellulose nitrate film may reach the 
theater, and this possibility may be 
with us for years to come. Entirely 



Samuel R. Todd: Safety Requirements in Projection 



213 



apart from this, . however, it has been 
shown that they lead to improved pro- 
gram presentation and better general 
safety conditions for both the public and 
the theater personnel. This is import- 
ant; twenty years of good engineering 
design and proven operational practices 
have created public confidence in theater 
safety. This could be destroyed by a 
single instance where loss of life was 



rightfully or wrongfully attributed to a 
relaxation in the presently accepted 
standards. Furthermore, it should be 
kept constantly in mind that there is 
no moral defense for anyone who may be 
responsible for deliberate laxity in the 
construction and operation of theater 
projection rooms if a fire does occur and 
the sordid picture of a disastrous panic 
is the tragic result. 



TELEVISION INSTALLATIONS 



Projection Rooms 

The equipment necessary in television 
station projection rooms creates possible 
hazards of the same type inherent in 
the projection rooms of motion picture 
theaters. With the present use of 35mm 
film and projectors equipped with the 
Synchro-Lite, instead of the conven- 
tional carbon-arc lamps, hazards affect- 
ing the safety of the operating personnel 
are definitely and continuously present. 
For example, this gas-discharge gap 
lamp employs potentials up to 5000 v 
across its terminals. The standard mo- 
tion picture projection equipment, as 
observed in television station projection 
rooms, consists of two 16mm projectors 
and two 35mm projectors, each equipped 
with the Synchro-Lite as the light source. 
As long as 35mm film continues to be 
used for programming purposes, the 
hazard inherent in the possible use of 
nitrate base film will require the ac- 
ceptance of safety regulations as here- 
tofore found necessary in the projection 
rooms of motion picture theaters. 

The panic that may be created by the 
sudden and violent combustion due to 
the ignition of perhaps a thousand or 
more feet of nitrate film, or the un- 
comfortable situation incident to one 
of the operating personnel lying prone 
from the effects of an electric shock, are 
possible situations requiring very special 
consideration from those individuals 
charged with the responsibility for 
formulating safety rules and regulations 
for television station projection rooms. 



The safety requirements for projection 
rooms in television stations should 
include as a minimum: (a) standard 
fireproof construction of the projection 
room; (b) the proper floor dimensions 
to provide good operating conditions; 
(c) approved storage facilities for the 
film; (d) an approved rewinding device 
for 35mm film; (e) the installation of 
approved, self-closing, automatically con- 
trolled fire shutters for the port holes; 
(f) the proper projection-room ventila- 
tion, including both gravity and forced- 
draft methods; and (g) the provision 
of adequate means for instant exit for 
the operating personnel through open- 
ings equipped with fireproof self-closing 
doors opening outward. As in the case 
of theater projection rooms, nearly all 
of these requirements are fully justified 
on a simple common-sense basis without 
any consideration of the special hazards 
introduced by the possible use of cellulose 
nitrate film. A typical television pro- 
jection room incorporating the design 
features which have been mentioned 
would be self-contained, having the 
moving picture machines project the 
light through a wall directly into the 
camera chain located in the adjoining 
room. Figure 1 shows in detail some 
of the safety features incorporated in a 
typical well-designed television studio 
projection room. 

Studios 

With the increasing use of a great 
variety of household appliances in the 
production of television programs, haz- 



214 



September 1952 Journal of the SMPTE Vol. 59 




' Fig. 1. A typical well-designed television studio projection room showing in some de- 
tail some of the safety features. 



ards are being introduced which require 
continuing alertness on the part of the 
producing and operating personnel. 
For example, in the demonstration of 
open-jet gas ranges the possibility of 
conflagration in the studio is always 
present. Perhaps to a lesser degree 
this also applies to the use and demon- 
stration of electric ranges and other 
electrical appliances with exposed heat- 
ing elements. 

In the larger studios, with arrange- 
ments for seating studio audiences of 



50 to 100 persons, the producing and 
operating personnel must ever be alert 
to unforeseen accidents that may cause 
a panic. Figure 2 shows a typical, large 
studio with the possibility of having 
large numbers of people confined within 
its walk and hence subject to all the 
usual and unusual panic hazards. In 
addition to the possible hazards just 
mentioned, special attention should be 
given to the safe installation of heavy 
lighting equipment, whether such equip- 
ment is directly suspended from the 



Samuel R. Todd: Safety Requirements in Projection 



215 



ceiling or mounted on balconies, and to 
adequate supports for heavy lighting 
units at the floor level. These pre- 
cautions should also apply to special 
rigging apparatus used to support and 
shift special scenic effects, and to all 
stage properties. In these larger studios, 
where relatively large groups of people 
are admitted, adequate exits with 
approved illuminated directional signs 
should be provided. Figure 3 shows the 
extent of the special lighting equipment 
and other production apparatus which 
may be encountered in a typical modern 
studio. 

Theater Television Using 
Direct Projection 

The installation of theater television 
equipment has introduced problems 
not heretofore present in providing 
motion picture screen presentations. 
Essentially, the equipment purchased 
by the theater owner for such an installa- 
tion consists of three major items: (a) 
a high-voltage supply unit weighing 800 
Ib and providing 20,000-v and 80,000-v 
output circuits; (b) video control ampli- 
fier units mounted on conventional racks 
and weighing 1200 Ib; and (c) a picture 
projection unit which with its mounting 
trunnion weighs 400 Ib. This by no 
means small extra weight of over a ton 
introduces a definite safety hazard to the 
building structure in many instances. 
Structural loading factors need to be 
thoroughly checked before the installa- 
tion of such massive equipment. 

Because of the high potentials pro- 
duced by the voltage supply unit it is 
essential that it be located in a separate 
fireproof room with the entrance door 
closed and locked at all times. It is 
preferable to locate the unit as near as 
possible to the optical barrel which 
encloses the picture projection tube in 
order to reduce the required length of 
the special 80,000-v cable which con- 
nects to the second anode of the picture 
tube. 



The video amplifier unit is mounted 
on two racks occupying a floor space 
40 in. wide and 18 in. deep extending 
to a height of 64 in. in the theater pro- 
jection room. It contains a television 
receiver, monitor panel, control panels, 
low-voltage power supplies and other 
miscellaneous operating units. While 
required projection-room space is not 
large, the room dimensions should 
provide enough to avoid overcrowding 
and consequent reduction in normal 
operating safety factors. 

The proper location of the picture 
projection tube and optical barrel is 
very important from the viewpoint of 
safety to the public and it is also a very 
important factor in securing best pro- 
jection quality. The nominal "throw" 
from the projection unit to the screen 
is 60 to 65 ft. In a typical installation, 
a heavy steel platform was installed for 
mounting the optical unit. This plat- 
form was mounted on the front face of 
the first balcony rail in such a manner 
as to preclude any possibility of un- 
authorized persons having access to or 
coming in contact with the projection 
tube or any of its high-voltage terminals. 
In this position, the tube and optical 
barrel projected a 15 X 20 ft picture on 
the screen at a "throw" of 62 ft. In 
theaters having no balconies the pro- 
jection unit must be supported from 
the floor or ceiling and, as in the case 
of balcony support, the mounting struc- 
ture must be adequately designed to 
eliminate any possibility of either elec- 
trical or mechanical hazards to theater 
personnel or audience. The unit should 
be enclosed in such a manner that any 
corona or arcing due to dampness is 
not visible. 

Presently available direct projection 
television equipment is very well de- 
signed from the viewpoint of having 
adequate safety disconnect switches at 
all points where dangerous potentials 
may be encountered. Switches are 
provided, for example, at the access door 
to the high-voltage power supply room, 



216 



September 1952 Journal of the SMPTE Vol. 59 




Fig. 2. A typical large studio showing the possiblity of accommodating large 

numbers of people. 




Fig. 3. A typical modern studio showing the extent of the special lighting equip- 
ment and other production apparatus which may be encountered. 



Samuel R. Todd: Safety Requirements in Projection 



217 



on the enclosure for the picture pro- 
jection tube and on various components 
of the amplifier and control equipment. 
It is extremely important that all of these 



safety circuits be intact at all times. 
Unauthorized modifications are the 
height of foolishness where potentials 
dangerous to life are concerned. 



FILM METHOD FOR THEATER TELEVISION PROJECTION 



This method, the so-called storage- 
type system, for television theater pro- 
jection uses a 35mm motion picture 
camera to photograph a negative image 
on a television receiver to produce a 
direct-positive print. The exposed film 
is transported continuously to equipment 
for rapid development and drying. 
From this equipment it is transported 
to the projector for immediate projec- 
tion on the theater screen. The elapsed 
time from the television camera pickup 
at the scene of action to the time of 
projection of the completed positive 
print on the theater screen is 61 sec. 

This method requires a properly 
ventilated room of fireproof construction 
for the television receiver, the 35mm 
picture camera with a magazine which 
may contain 12,000 ft of unexposed 
film, and for the developing and drying 
equipment. This room obviously must 
be adjacent to the theater projection 
room and provision must be made for 
feeding the completed positive print 
to the upper fire valve rollers of the 
theater projector, from which the upper 
magazine has been removed. This 
arrangement of equipment will provide 
a continuous projection of motion pic- 
tures on the theater screen for more 
than two hours' duration. 

From the viewpoint of safety, the 
present method used for feeding the 
processed print to and across the 
theater projection room to the projector 
head on a series of open pulleys could 
hardly be considered as complying with 
the most elementary standards for safe 
handling of 35mm film. 

With the take-up magazine and the 



take-up device on the projector de- 
signed for only approximately 2000 ft 
of film, it is obvious that cutting of the 
film at the end of each 2000 ft will be 
required. The running end of the film 
must quickly be attached to the hub of 
an empty reel and the excess film on the 
projection-room floor must be spun 
onto the hub, after which the reel must 
be placed into position on the take-up 
spindle of the lower magazine for taking 
up the succeeding 2000 ft of film. This 
procedure must be repeated five times 
during the continuous projection of 
1 2,000 ft of film. Such a procedure does 
not appear to follow any of the long- 
standing practices for the safe handling 
of motion picture film. 

Conclusions 

Some of the safety hazards in theater 
and television studio projection rooms 
have been pointed out and the import- 
ance of adequate corrective measures 
has been emphasized. The special safety 
precautions developed over a long period 
for theater projection rooms have been 
shown to be sensible and desirable 
without regard to the ignition charac- 
teristics of the film used, and the same 
considerations are shown to be ap- 
plicable also to television studio pro- 
jection rooms. Special hazards in tele- 
vision studios have been outlined. 
Theater television equipment, which 
presents safety hazards of new types, 
has been discussed and attention has 
been called to some of these in the hope 
that full knowledge of them will aid in 
their eventual elimination. 



218 



September 1952 Journal of the SMPTE Vol. 59 



Military-Type Lenses 

for 35mm Motion Picture Cameras 



By PAUL G. FOOTE and R. E. MIESSE 



A new series of lenses for 35mm motion picture cameras has been designed as 
the first to primarily meet the many detailed requirements of military use. 
These are designated by the name Millar, and represent the achievement 
of new goals. It has been a joint development by two companies who pooled 
resources and experience to provide a series in a minimum of time and cost 
with high performance. Many mechanical features have been combined 
with top optical performance to provide dependable operation over a wide 
range of conditions. 



1. General Description 

The Miltar series of lenses was 
planned to incorporate features required 
for military use, but not generally pro- 
vided in lenses made for commercial or 
studio use. In specifications for either 
lenses or cameras appear requirements 
for vibration, humidity and temperature 
range tests more stringent than any 
commercial needs, which were con- 
sidered in all details of the design of these 
lenses. Wherever possible, the recom- 
mendations of MIL-STD-150 were fol- 
lowed. In the specification list of lens 
types, these are: "Type V, for 35mm 
motion picture cameras." 

The series is available in black for 
general use, as shown in Fig. 1. There 
is also a series in gray for the A-6 
Camera, a portable 35mm motion 

Presented on April 22, 1952, at the Society's 
Convention at Chicago, 111., by Paul C. 
Foote, Bell & Howell Co., 7100 McCormick 
Rd., Chicago 45, 111., and R. E. Miesse, 
General Scientific Corp., 5151 W. 65 St., 
Chicago, 111. 



picture camera for the Government 
services. 

The equivalent focal lengths of the 
lenses in the series are based on a 
modified geometric progression of ap- 
proximately V2, or 1.4X intervals, 
which give an area change of 2 from 
one lens to the next (Fig. 2). These are: 



1-in., 25mm 
1.4-in., 35mm 
2-in., 50mm 
3-in., 75mm 



4-in., 100mm 

6-in., 152mm 

10-in., 254mm 



The 3-in. and 6-in. depart slightly 
from the exact values in the series 
because of the previous use of these 
focal lengths, and the 10-in. was included 
for the same reason. The first pro- 
duction included all but the 1.4-in. 
and 3-in., but these are now available. 

The focal length of all lenses has been 
coded by the use of dots just ahead of 
the word "feet" on the focusing jacket 
in order that matched pairs, for stereo 
or other uses, could be picked from 
production lots without needing further 



September 1952 Journal of the SMPTE Vol. 59 



219 




Fig. 1. Miltar Series in black for general use. 



Fig. 2. 



measurements. It keeps high focusing 
scale accuracy without individual cali- 
bration. Focal lengths are segregated 
into three groups, which are 

plus 2% to plus 1%, three dots, 
plus 1% to minus 1%, one dot, and 
minus 1% to minus 2%, two dots, 

and assembled into the focusing jackets 
that have been engraved, particularly 
for each group, and coded in accordance 
with the above ranges. The majority 
of the lenses fall into the nominal group: 
plus 1% to minus 1%, one dot. 

These lenses are mounted in 
military standard mount (Fig. 3) also 
identified as the Bell & Howell Eyemo 
mount, but they will also be availabl 
unmounted, or mounted in studio-type 
focusing jackets for the Bell & Howell 

Graph of effective focal length Design 2709, the Mitchell, Wall or other 

and magnification steps. cameras. 



IU 

6 

4 


MILTAR LENSES 
FOCAL LENGTH PROGRESSION / 


7 


" 








/I 




Xh 

HICAGC 




z 






/ 




WELL 
EPT. C 


2 
1.4 


LENGTH- 






/ 




a HO 

ENG.D 


3 
S 




/ 




BELL 
riCAL 

TION 




/ 


MAG 


op- 

MIFIC/ 




L4 2 2.8 4 5.6 8 1 



220 



September 1952 Journal of the SMPTE Vol. 59 



2. Optical Characteristics 

In mapping out this Miltar series, 
some limitations were imposed on 
diameters to permit mounting lenses on 
existing camera turrets. The type of 
lens was then chosen to provide maxi- 
mum performance. The 1-in. through 
4-in. are 6-element construction of the 
Speed Panchro or Biotar form, with 
apertures of //2, or T2.2. 

The size restrictions limited the 6-in. 
to//3.5, or T3.7, permitting the use of a 
well corrected triplet. The 10-in. is 
limited to //4.5, or T4.9, and is a 4- 
element telephoto of standard form. 
In each case a special effort was made to 
use readily available domestic glass. 

This glass, however, is held to closer 
than normal commercial index and 
dispersion tolerances. 

The performance of all focal lengths 
is substantially increased over lenses 
previously supplied and is comparable 
to the best studio lenses. The aberra- 
tions have been corrected to give a crisp, 
high contrast image over the full frame. 

The curves showing the aberration 
corrections are given in Figs. 4, 5, 6, 
7, and 8. Part of the information is 
from the design data, part from actual 
measurements of production lenses. 

No attempt is made here to quote 
resolution values, as the performance 
requirements of these lenses are based 
on results in specific cameras. Tests on 
spectroscopic plates do not give com- 
plete information, and tend to give a 
false appraisal of the practical values 
because of contrast differences. 

Vignetting has been reduced on all 
focal lengths. This has required es- 
pecially careful balancing of the oblique 
aberrations to obtain the improved 
contrast and resolution in the outer 
portions of the frame. 

All air-glass surfaces are coated. 
Cemented elements will withstand the 
full temperature range and thermal shock 
requirements of the specifications. 



3. Mechanical Characteristics 

In the styling and general design, care 
was taken to give the lenses a matched 
series appearance. The diameters and 
physical lengths are in steps to correspond 
with the focal lengths and apertures. 
Special attention has been given the 
mounts and glass to obtain rugged con-, 
struction for meeting thermal shock, 
temperature range, humidity, vibration 
and mechanical shock tests. 

In designing this series to meet the 
drastic vibration requirements, every 
part is locked into its respective assembly 
with special antivibration sealing com- 
pounds and deep-set pilot screws, which 
again are locked into place so securely 
that they can only be removed by 
drilling. 

The lenses are completely operable 
over the temperature range of 65 F 
to +160 F. All tolerances have been 
computed to offset the size changes for 
expansion and contraction through the 
temperature ranges. 

A special noncorrosive lubricant is 
used which is not affected by these 
changes. This lubricant has a vapor 
pressure so low at 160 that no deposit 
on the glass is detectable after sustained 
operation at that temperature. 

The diaphragm blades are lubricated 
with an unusual type of material, 
guaranteeing perfect operation over 
the full temperature range, with a long 
operating life. It has the properties 
of being anti-icing and noncongealing, 
at extremely low temperatures. Glob- 
ules of condensed moisture will not 
freeze to the leaves, and the lubricant 
itself will not allow any of the leaves to 
bind together. 

All metal parts, internal and external, 
are finished for high corrosion resistance. 
All aluminum parts are black anodized. 
Antireflection scoring and a durable 
optical black are used on all surfaces 
where required, internally and ex- 
ternally. A high-quality baked syn- 
thetic enamel is bonded to exterior 



Foote and Miesse: Military-Type Lenses 



221 




50 'MM ftKD LONGER. 
FOCAL, L.EMGTHS 



25 AMD 35 MM 
FOCAL LENGTHS 



* A*.OOO15* E.F.L.* T MAX. 
0MtMS\OMS M INCHES 

Fig. 3. Lens and camera mounting dimensions from MIL Specification. 



parts, resulting in a finishing system 
that is extremely durable. 

At present, the series is available in 
two external enamel finishes: gray, to 
match a camera on which they are 
used; and black, for general service use. 

All control rings are adequately 
separated and are made as large as 
diameter clearances permit, with broad 
spaced knurls that facilitate easy manipu- 
lation, even though the operator may 
be wearing gloves. Focusing and iris 
scales are marked in easily read charac- 
ters, especially designed (for all Bell & 
Howell lenses, not limited to this series) 
to prevent confusion of such characters 
as 3, 6 and 8, etc. The markings include 
full identification of the lens, its type, 
focal length in both inches and milli- 
meters, filter size, sunshade thread, etc. 
The iris and focusing scales are de- 
signed to be read from the camera end. 
The lens name and filter information 



is designed to be read from the front of 
the lens. 

Special provision has been made to 
mount standard sized filters between 
sunshade and lens in a convenient recess 
divided between both, so when the 
sunshade is screwed in, the filter is 
trapped, and protected by the sunshade 
(Fig. 9). The filter can be easily 
inserted regardless of the position of the 
camera. If the lens is pointed down or 
held on the level, the filter can be 
dropped into the recess on the sunshade, 
and the sunshade screwed into the lens. 
If the lens is pointed up, the filter can 
be dropped into the recess on the lens 
mount, then trapped when the sunshade 
is screwed into place. The filter sizes 
are recognized industry standards (Table 
I). The lens mounts have been de- 
signed to use as few sizes as possible. 
Four are required for this entire series: 
1 using size 5, 2 using size 6, 1 using 



222 



September 1952 Journal of the SMPTE Vol. 59 



LENS RECEPTACLES, DESA-&A CAMERA 

3.3.2.10.4- 

DETAIL'A" SCALE: V*r 

THREAD 



MIL-C-4052(U.S.A.F.) 



LErtS AUGrtMEKlT KEY DETAILED *B 



- LCNS LOCKIM6 Pl4. DETAILED C 
LENS SEAT LOCK. 




0*Z ,1252 
oo> " f -.oo\*; 



(MCHES UNLESS 

OTHERWISE SPECIFIED 

TOLERAMCES- FRACTIONS *ooS 



size 7, 3 using size 8. Thread sizes 
and mount diameters have been kept 
to military and ASA standards. The 
sunshades have also been standardized 
to these specifications and marked with 
the filter size they retain. 

Click stops are provided on the iris 
scales to prevent accidental movement 
and provide easily identified positioning. 
Lenses are available in either //stops 
or individually transmission-calibrated 



Table I. FUters. 



Size 


Nomi- 
nal 
Size, 


Max. 


0. 


D. 


Max. 
Thickness 


No. 


in. 




in. 


mm 


in. 


mm 


5 


1 


I 


.198 


30 


.43 





.175 


4. 


45 


6 


H 


1 


.634 


41 


.5 





.195 


4, 


95 


7 


2 


2 


.006 


50 


.95 





.219 


5. 


55 


8 


2\ 


2 


,506 


63 


.65 





.226 


5. 


75 



Foote and Miesse: Military-Type Lenses 



223 



-ss 
01 



h- o 



LLJ O oj 

C w 

(V i. uj 

O ? 

u 5- 



35 -3 

lT> Q 



!< 




> > 



i.g 



5^Q 

Zou 



I L 




vOUJ 

in or 



rss 



ifl (J 

o^ 
\o _j 



QIL. 



u tt 

* Wg o 



Z uiO 



224 



September 1952 Journal of the SMPTE Vol. 59 



t 

Uin 
K 

S* 

ol 

QL ~ 

51 



g 




N'5' 
o 



*!O 
S~ntf 



g o< 
S ^>2 



O 
In ^* 





Foote and Miesse: Military-Type Lenses 



225 



S 



U(n 
&$ 

<J UJ 

So^ 

P 

a?* 



S*' 

-I 

*> 
> 



e 



3 _ 


o^ 
t?5 




/ /- 
/ / - 

/ ' ~ 


5 l! 

a j tf 




1 ~I 
r _ 
i 
i - 


i 5'5 

? < a: 
^3f 

u\ \T* ~7 O ^ 

^ w , <c. u. 5 




/ 


I s 1^ 

Sli 


- 


> > 



SIXV WOad AW/v\V 

o 



T 



VOUJ 
mot 

vO 

vno 
sz 
o < 



K xcS 

^^ a 





2 
1 

U 

I 

a 
O 



r 
bo 



226 



September 1952 Journal of the SMPTE Vol. 59 



C5> 

LLJ 

b 

(Y 






c^ 

z w : 


N 
ft i 


I j 


1 
< 




\\ ] 


* * < 

* 
\n 

(A * 


HI 


| i 

8 S ! 

10 ! 

< 


QI*W WOMH XWMW 






o ? 





S3HDNI Nl C V 
/ D M 

1 8 

o ? I" 



p 






X . c ,'' . "^^ 

(fl oo \r\/ o ^^?N o 
pt-M^cu <\J 8} ii^^ in 

55 i ,/ i , , , , 1 , , i i I i i i , | i rr-r-^Lj i ~ 


ph )C (o ^^^" 


(f) ( ^^^N-_ _^ ^^- -^"^^^"^ 


< h- ' 


Q 


UJ 


(tt: * 

si i 


1^ i 

|ii ii 

|5u 3^ 

^< *,, ovft 
|g &s|^ ^;< : 


q 

I 

in 



O^^ ^ "T ^? ' -X / ' 




uja? zo^' ^ \ X^ " 




IO 5riUJU-' . \ / - 




HU. D^- 1 -* \ / 


r 




f 


^ <fi V / 


if\ 


om< ^^^ 





_j<u.in - 


i 


^ 







1 



Ix 

bio 



Foote and Miesse: Military-Type Lenses 



227 











LU 














( 

LU 


%? 












or 














oc 


* Ul 












o 




u 












o; 

LU 



~^ 


I? -* 












\ 


100 








K ' _ 
Uin 




p 


LU 

5 




< 


fe 

S 


5 

tt 




/ 


8 1 




UJ 
Q. 
< 
_j 




O 

or 


< 

2 






/ ~ 


or 
i ^ 


^ 

0. 


tt' 

LU 


\ 


~T 


X 
CJ 


K 

lf> 

S 


S 

^ 

^ 


X 
\ 
N 
X 


\ 


^o 

v , 


h- 
< 


J 

n 


a! 

C 


in 

Ul 




tTi 

^ 

I 


s 

\ 
\ 


\ 


m-J 

a*< 

SujZ 


r> 
u 




r 

h 

3 






LU 


r> 
>-> 


Z 




\ \ 


oq 


1 


H 


I 
< 



b. 







\ \ 


10 J 

o^ K 


Z 
t- 


S 


_J 


| 






\ \ 

\ V 


8 g 


0, 



J 
< 




t/> 
> 






\ V 




1 


_l 


y 

h- 

a 








SIXV* WObd AV/v\V 


__J 

o 

u^ 


--' 


UJ 

> 








7TN 


1HOI3H V 










? 




! c 










1 


i i i I 1 1 i i 


1 1 , , , , 1 








3 




I 10 0_ 



3 

1 




1,111 


i i i i 1 i 




i i i 1 i i i t 1 


K 

+ / T 


x 

C\J If 

1 1 



228 



September 1952 Journal of the SMPTE Vol. 59 




Fig. 9. The 4-in. lens, showing caps, sunshade and filter. 



T stops. All scales are spread with 
uniform spacing between stops. This 
has been obtained by the use of a modi- 
fied L-shaped iris leaf. Iris and focusing 
scales either work to a common index 
line, or to index lines on the same axis. 
Locks have been provided to clamp the 
focusing mount at any position. All 
distances are measured to the focal 
plane. 

Two types of mount are provided. 
For the 3-in. and shorter lenses, these 
are the same as previously supplied, 
only of a much sturdier construction, 
and the focusing and iris rings have 
been brought forward from the camera 
for better accessability. On these 
mounts, the focusing is accomplished 
by rotating the focusing sleeve between 
the lens and the mount on the camera. 
A key in the camera keeps the lens from 
rotating. The focus position is locked 
by the clamp screw normally provided 
on the camera. 

For the 4-in. and longer lenses, an 
entirely new focusing mount has been 
developed, common to all three lenses. 
A stainless steel adapter mounts the 
entire assembly into the camera, and is 
locked in position by the camera clamp- 
screw. The focusing action is inde- 
pendent of this. The key orients the 
lens to bring focusing and iris index 




fig. 10. Rear view of 2-in. and 4-in. 
lenses. 



marks into the operating position (Fig. 
10). Stainless steel was chosen because 
of its high shearing modulus and its 
ability to withstand fatigue at the 
junction between the camera turret and 
the lens body. Further, it is electro- 
lytically inert with the camera turret. 
A red dot is placed on the flange focusing 
seat of the adapter in direct line with 
the bayonet slot, which enables the 
easy mating of the slot and the bayonet 
when inserting the lens into the camera. 
A square aperture in the adapter 
which allows added internal clearance 
for the light beam to the corners of the 



Foote and Miesse: Military-Type Lenses 



229 



-SMw 






.' iv %: 




E H 



CO SZir.' 



230 



September 1952 Journal of the SMPTE Vol. 59 



frame is positioned by taking advantage 
of the slot. 

The focusing jacket deserves special 
comment. Because of the weight of the 
lenses, a sturdy mount is required 
(Fig. 11). The focusing threads are 
nominally square, but the sides have a 
few degrees taper for ease of manu- 
facturing, and to provide a good fit. 
They have been perfection-lapped with 
special noncharging compounds in order 
to maintain smooth operation and long 
life at all temperatures. 

The outer sleeve is made in two 
separated sections, spring loaded for 
accurate positioning. The focusing 
lock, when applied, operates in the same 
direction as the loaded spring; thus, a 
rigid, exact station of focus is acquired. 
When the knurled lock ring behind the 
focusing ring is turned, the floating 
section of the sleeve is pushed away 
from the main stationary section, clamp- 
ing the threads axially on the internal 
sleeve or screw. 

These lenses are all flange focused 
on an internal flange. Consequently, 
there is no defacing of any outside 
surfaces. The trimming dimension is 
held within plus or minus 1/20 of 1%, 
to plus or minus 1/33 of 1%, depending 
on the particular focal length of the 
lens in the series. Special equipment 
had to be designed in order to measure 
and maintain these very close dimen- 
sions. 

Provision has been made to add Depth 
of Field Scales when required. 

A new design dust cap is provided 
(Table II). It is black molded cold- 
resistant synthetic rubber with a metal 
insert, giving the stiffness and protection 
of an all-metal cap and the grip of a 

Table II. Lens (Dust) Caps. 



Size 

No. 



For Diameters 



in. 



mm 



1.870 47.5 
2.244 57.0 
2.744 69.7 



rubber cap. Because of size standardi- 
zation, each cap fits the lens with or 
without the sunshade. 

The following tabulation gives lens 
nomenclature, mount characteristics, and 
accessory sizes: 

1-in. (25.5mm} f/2 (T2.2) 

Focuses from infinity to 1 ft 

Iris calibrated from//2 to //22 (T2.2 to 
T22) 

Filter size 6 (1$ in.) 

Sunshade size 6-7 

Gap size 7 
1.4-in. (35mm)f/2(T2.2) 

Focuses from infinity to 1.5 ft 

Iris calibrated from f/2 to f/22 (T2.2 to 
T22) 

Filter size 5 (1 in.) 

Sunshade size 5-6 

Gap size 6 
2-in. (50mm) f/2 (T2.2) 

Focuses from infinity to 2.5 ft 

Iris calibrated from f/2 to f/22 (T2.2 to 
T22) 

Filter size 6 (H in.) 

Sunshade size 6 

Gap size 6 
3-in. (75mm) f/2 (T2.2) 

Focuses from infinity to 5 ft 

Iris calibrated from f/2 to f/22 (T2.2 to 
T22) 

Filter size 7 (2 in.) 

Sunshade size 7 

Cap size 7 
4-in. (100mm) f/2 (T2.2) 

Focuses from infinity to 4 ft 

Iris calibrated from f/2 to f/22 (T2.2 to 
T22) 

Filter size 8 (2% in.) 

Sunshade size 8 

Cap size 8 
6-in. (152mm} j I 3.5 (T3.7) 

Focuses from infinity to 10 ft 

Iris calibrated from//3.5 to f/22 (T3.7 to 
T22) 

Filter size 8 (2| in.) 

Sunshade size 8 

Gap size 8 
10 in. (254mm) f/4.5 (T4.9) 

Focuses from infinity to 25 ft 

Iris calibrated from //4.5 to f/22 (T4.9 
to T22) 

Filter size 8 (2% in.) 

Sunshade size 8 

Cap size 8 



Foote and Miesse: Military-Type Lenses 



231 



In the design of these lenses, special 
engineering and manufacturing tech- 
niques have been applied, which insure 
concentricity. The factors contributing 
most to these goals are: 

7. The Optical Centering of the Elements: 
Special equipment assures a high degree 
of accuracy in centering before and after 
cementing. 

2. The Alignment of the Elements in 
Their Cells: The basic geometry of the 
thick edges, plus thick spacers, and the 
parallel seats, assure an optical-me- 
chanical self-alignment with remarkable 
accuracy and without imposing im- 
possible tolerances. 

3. The Smooth Fit of the Threads: No 
threads are generated by taps and dies. 
Retaining ring threads are chased parallel 
and square to the bore. 

4. The Piloting of Cells and Focusing 
Mounts: Where higher accuracy is re- 
quired, pilots and threads are used. 
The threads only to retain, and the pilots 
to guide and locate. Operational 
threads are lapped. 

All of this is obtained without a 
sacrifice to production possibilities. The 
parts are held to such precision that 



there is an absolute minimum of hand 
fit required, which in turn insures a 
production in keeping with any normal 
requirements that could be placed upon 
us within the realm of reason or economic 
limits. 

Patents have been applied for on all 
of these lenses. Due to the newness of 
this development, sufficient time has 
not elapsed to receive patent office 
action. 

While being currently supplied to the 
military services, it is felt that this series 
contains features of value to others and 
so will be commercially available. 

The authors wish to give special 
commendations to the staffs of both 
General Scientific Corp. and Bell & 
Howell Co. for the splendid help in the 
design, development, testing and pro- 
duction of the Miltar lenses. 

Discussion 

John D. Hayes (Bausch & Lomb Optical 
Co.): I'd like to ask the authors how they 
obtained sealing for humidity around the 
iris diaphragm slot in the barrel? 

Mr. Foote: There is no sealing for hu- 
midity. The operational requirements of 
the lens do not specify that in this par- 
ticular case. 



232 



September 1952 Journal of the SMPTE Vol. 59 






CORRECTION PH22.1 1-1952 
16Mm Motion Picture Projection Reels 



IN THE PROCESS of revising Z22.ll, several drafts were considered by the 
16mm and 8mm Motion Pictures Committee. In December 1949, SMPE 
121 was issued containing a misplaced decimal point in the lateral runout 
dimension of 200-ft reels (Table 2). Thus, the correct dimension of .057 
in. was given as 0.57 in. This error was discovered only after the final 
approved standard was published in the June 1952 Journal. The standard 
is therefore now being republished as originally intended. 

In addition, the diagram has been changed slightly to show the flanges 
flat instead of flared to preclude any misunderstanding that the edges must 
be rolled or flared. The words "if any" have been added at the end of the 
note after "S" in the table of dimensions to make that clear. 



September 1952 Journal of the SMPTE Vol.59 233 



American Standard 


ASA 










Ktg. U. S. Pal. Off. 


for 








PH22. 11-1 952 










Revision of 


16-Millimeter Motion 


Picture 


Z22.II.I94I 

and 


Projection Reels 


Z52.33-I945 


*UDC 778.55 










Page 1 of 4 pages 








hw- 


-AT PERIPHERY 

Qi ) 


/< "N 








*w-* 


-AT CORE ; 








j*f> 


1 _ 




/ f "\ 1 \ 






ENLARGED VIEW OF HOLE N 

FLANGE ON LEFT IN SECTIONAL 


tf ^^^ x ^ ( I 






VIEW SHOW 


N ABOVE 


ji IGl '! ^ 


p 


*-w~* 


V AT SPINDLE 




\ V^ 1 / 


f 


vwr 


T r*~ B ~ 

T~l 










iJZ 


y? 


ks-| 

Table 1 


ENLARGED VIEW OF HOLE N 
FLANGE ON RIGHT IN SECTIONAL 
VIEW SHOWN ABOVE 

See page 3 for notes. 




Dimension 


Inches 


Millimeters 






A 


0319 +0.000 

' 319 -0.003 


8.10 + 


0.00 






B 


0319 +0.000 

' 319 -0.003 


8.10 1; 


).08 






R 1 


0.790 maximum 


20.06 maximum 






S 2 (including flared, 


















rolled, or beveled 


0.962 maximum 


24.43 maximum 






edges, if any) 


















T (adjacent to 


0.027 minimum 


0.69 minimum 






spindle) 


0.066 maximum 


1.68 maximum 






U 


0.312 0.016 


7.92 0.41 






V 


ftlo - +0.005 

-o.ooo 


318 +ai3 
3 ' 18 -0.00 






W, at periphery 3 


0.66 







)45 
325 


16<76 -a64 






at core 4 


0.660 0.010 


16.76 0.25 






at spindle holes 


0.660 0.015 


16.76 0.38 






Flange and core 
concentricity 5 


0.031 


0.79 








Approved April 30, 1952, by the American Standards Association, Incorporated 


Sponsor: Society of Motion Picture and Television Engineers 


Univerwl Decimal Classification 



Copyright, 1952, by American Standards Association, Inc.; reprinted by permission of the copyright holder. 



234 



September 1952 Journal of the SMPTE Vol. 59 



American Standard 


ASA 

Rr e . V. S. Pal. Off. 


for 




16-Millimeter Motion Picture 


PH22.1 1-1952 


Projection Reels 




Page 2 of 4 pages 




Table 2 




Capacity 


Dimension 


Inches 


Milli- 
meters 


Capacity 


Dimension 


Inches 


Milli- 
meters 


200 feet 
(61 meters) 


D, nominal 
maximum 
minimum 


5.000 
5.031 
5.000 


127.00 
127.79 
127.00 


1200 feet 
(366 meters) 


D, nominal 
maximum 
minimum 


12.250 
12.250 
12.125* 


311.15 
311.15 
307.98* 






C, nominal 
maximum 
minimum 


1.750 
2.000* 
1.750 


44.45 
50.80* 
44.45 




C, nominal 
maximum 
minimum 


4.875 
4.875 
4.625* 


123.83 
123.83 
117.48* 








Lateral 
runout, 7 
maximum 


0.057 


1.45 




Lateral 
runout, 7 
maximum 


0.140 


3.56 




400 feet 
(122 meters) 


D, nominal 
maximum 
minimum 


7.000 
7.031 
7.000 


177.80 
178.59 
177.80 


1600 feet 
(488 meters) 


D, nominal 
maximum 
minimum 


13.750 
14.000* 
13.750 


349.25 
355.60* 
349.25 






C, nominal 
maximum 
minimum 


2.500 
2.500 
1.750* 


63.50 
63.50 
44.45* 




C, nominal 
maximum 
minimum 


4.875 
4.875 
4.625* 


123.83 
123.83 
117.48* 








Lateral 
runout, 7 
maximum 


0.080 


2.03 




Lateral 
runout, 7 
maximum 


0.160 


4.06 




800 feet 
(244 meters) 


D, nominal 
maximum 
minimum 


10.500 
10.531 
10.500 


266.70 
267.49 
266.70 


2000 feet 
(6 10 meters) 


D, nominal 
maximum 
minimum 


15.000 
15.031 
15.000 


381.00 
381.79 
381.00 






C, nominal 
maximum 
minimum 


4.875 
4.875 
4.500* 


123.83 
123.83 
114.30* 




C, nominal 
maximum 
minimum 


4.625 
4.875 
4.625 


117.48 
123.83 
117.48 








Lateral 
runout, 7 


0.120 


3.05 




Lateral 
runout, 7 


0.171 


4.34 








maximum 








maximum 








*When new reels are designed or when new tools are made for present 
reels, the cores and flanges should be made to conform, as closely as prac- 
ticable, to the nominal values in the above table. It is hoped that in some 
future revision of this standard the asterisked values may be omitted. 



September 1952 Journal of the SMPTE Vol. 59 



235 



American Standard 

Re t . V. S. Pat. Of. 



for 

16-Millimeter Motion Picture 
Projection Reels 



PH22.11-1952 



Note 1: The outer surfaces of the flanges shall be flat out to a diameter 
of at least 1.250 inches. 

Note 2: Rivets or other fastening members shall not extend beyond the 
outside surfaces of the flanges more than 1 732 inch (0.79 millimeter) and 
shall not extend beyond the over-all thickness indicated by dimension S. 

Note 3: Except at embossings, rolled edges, and rounded corners, the 
limits shown here shall not be exceeded at the periphery of the flanges, 
nor at any other distance from the center of the reel. 

Note 4: If spring fingers are used to engage the edges of the film, dimen- 
sion W shall be measured between the fingers when they are pressed out- 
ward to the limit of their operating range. 

Note 5: This concentricity is with respect to the center line of 'the hole for 
the spindles. 

Note 6: This reel should not be used as a take-up reel on a sound projector 
unless there is special provision to keep the take-up tension within the 
desirable range of 1 Vb to 5 ounces. 

Note 7: Lateral runout is the maximum excursion of any point on the flange 
from the intended plane of rotation of that point when the reel is rotated 
on an accurate, tightly fined shaft. 



236 September 1952 Journal of the SMPTE Vol. 59 



American Standard 
for 

16-Millimeter Motion Picture 
Projection Reels 


ASA 

Kef . V. S. Pat. Off. 

PH22.11-1952 



Page 4 of 4 page* 



Appendix 

(This Appendix is not a part of the American Standard for 16-Millimeter 
Motion Picture Projection Reels, PH22. 11-1 952.) 

Dimensions A and B were chosen to give sufficient clearance between the 
reels and the largest spindles normally used on 16-millimeter projectors. 
While some users prefer a square hole in both flanges for laboratory work, 
it is recommended that such reels be obtained on special order. If both flanges 
have square holes, and if the respective sides of the squares are parallel, the 
reel will not be suitable for use on some spindles. This is true if the spindle 
has a shoulder against which the outer flange is stopped for lateral position- 
ing of the reel. But the objection does not apply if the two squares are ori- 
ented so that their respective sides are at an angle. 

For regular projection, however, a reel with a round hole in one flange is 
generally preferred. With it the projectionist can tell at a glance whether or 
not the film needs rewinding. Furthermore, this type of reel helps the pro- 
jectionist place the film correctly on the projector and thread it so that the 
picture is properly oriented with respect to rights and lefts. 

The nominal value for W was chosen to provide proper lateral clearance 
for the film, which has a maximum width of 0.630 inch. Yet the channel is 
narrow enough so that the film cannot wander laterally too much as it is 
coiled; if the channel is too wide, it is likely to cause loose winding and ex- 
cessively large rolls. The tolerances for W vary. At the core they are least 
because it is possible to control the distance fairly easily in that zone. At the 
holes for the spindles they are somewhat larger to allow for slight buckling 
of the flanges between the core and the holes. At the periphery the toler- 
ances are still greater because it is difficult to maintain the distance with 
such accuracy. 

Minimum and maximum values for T, the thickness of the flanges, were 
chosen to permit the use of various materials. 

The opening in the corner of the square hole, to which dimensions U and 
V apply, is provided for the spindles of 35-millimeter rewinds, which are 
used in some laboratories. 

D, the outside diameter of the flanges, was made as large as permitted 
by past practice in the design of projectors, containers for the reels, rewind's, 
and similar equipment. This was done so that the values of C could be made 
as great as possible. Then there is less variation, throughout the projection 
of a roll, in the tension to which the film is subjected by the take-up mech- 
anism, especially if a constant-torque device is used. Thus it is necessary to 
keep the ratio of flange diameter to core diameter as small as possible, and 
also to eliminate as many small cores as possible. For the cores, rather widely 
separated limits (not intended to be manufacturing tolerances) are given in 
order to permit the use of current reels that are known to give satisfactory 
results. 



September 1952 Journal of the SMPTE Vol.59 237 



72d Semiannual Convention 



The Tentative Program, mailed to all members on August 29, shows the schedule 
for 86 papers and Committee Reports. Sixteen Committee Meetings will be held 
during the week. Of the 86 papers, 41 are for the International Symposium on 
High-Speed Photography which is scheduled to begin on Wednesday morning, 
October 8, with successive sessions originally scheduled through Friday forenoon. 
Current developments may require Program Chairman Joe Aiken to revise this so that 
the Symposium is carried through Friday afternoon. In that case, the last three 
papers scheduled for Thursday afternoon at the Naval Ordnance Laboratory may 
be moved to a Symposium session, and certain special motion picture papers would be 
scheduled for the Naval Ordnance Laboratory Session. For the NOL Session, note 
this advice repeated from the Tentative Program : 

All individuals who wish to go on the trip to the Naval Ordnance Laboratory on 
Thursday, must register for it prior to noon Tuesday, October 7. Those who wish to 
attend this session, but who cannot register before noon Tuesday, must write their 
intention to Joseph E. Aiken, 116 N. Galveston St., Arlington 3, Virginia, and state if 
they are citizens of the United States. 

All non-citizens of the United States must receive a special clearance for the Naval 
Ordnance Laboratory visit. This may be obtained by writing to their embassy in 
Washington, prior to the Convention, requesting that they be cleared for this visit to 
the Chief of Naval Operations, who will in turn notify the Naval Ordnance Laboratory. 

Plans for the first two days remain essentially the same as in the Advance Postal 
Card Notice Television Sessions on Monday afternoon and evening and on Tues- 
day forenoon and afternoon, and a General Motion Pictures Session Tuesday evening. 

Those who do not yet have hotel reservations should write Air Mail or wire Mr. 
H. C. Blunck, Manager, Hotel Statler, Washington, D.C. Ask Society headquarters 
for information or copies of the Tentative Program if you would like such. 

Board of Governors Meeting 

A major portion of the Society's Board tions and possibilities for a project control 

Meeting on July 17 was a continuation and scheme that would formalize the course of 

reflection of what was previously reported Society projects. These Board actions have 

as "Most significant administrative develop- resulted in Proposed Bylaws, 

ment of 1951 . . ." (report of this year's One proposed additional Bylaw records 

first Board Meeting). This has been the the long-established underlying policy that 

appointment and operation of an Execu- Standards and Recommendations de- 

tive Committee. veloped by the Society are of a voluntary 

From the Executive Committee's atten- nature. The other Bylaw meets the 

tion to some major details and aspects of legal technicality of providing for a pro- 

the Society's operation have come logically cedure for disposition of assets in case of dis- 

and with minimum pain several sum- solution. These proposals were explained 

mations of points of policy for the Board's in detail in the August Journal, p. 153. 
consideration. The Board also reviewed 

the initial outline of a study of the costs of Test Films 
membership service and of the costs of 

securing new members. Action was taken The Board reaffirmed the Society's 

on the resignation of one Society Officer policy of developing and supplying test 

and policy was carefully reviewed in regard films on a no-profit, no-loss basis. The 

to another office. appropriate officers and employees were 

The Executive Committee has been instructed to make whatever cost account- 
studying and reviewing some legal prob- ing analyses, surveys and sales forecasts are 
lems, accounting policies, test film opera- necessary to maintain the policy of supply- 

238 



ing test films as a part of the Society's gen- 
eral program for the development of tech- 
nical and engineering standards. 

Membership Cost Study 

The Executive Secretary presented a 
brief report of progress on the Head- 
quarters' cost study of membership service, 
explaining that this first official attempt to 
separate the Society's various operations for 
the purpose of cost analysis was encourag- 
ing. Comparisons were drawn between 
dues paid by the average member and cost 
of services rendered, and then between the 
first year's dues of a new member, the cost 
to secure each additional new member, and 
the added cost to the Society of services 
rendered to a new member during his first 
year. It is expected that the completed 
study will be the basis for detailed planning 
of the many Society activities. 

Finances and Budget 

The six-month reports of the Financial 
Vice-President and the Treasurer were ap- 
proved. The Executive Secretary made a 
preliminary report on the 1953 budget, and 
the Board made recommendations as the 
basis for further budget planning, so that 
a proposed 1953 budget can be considered 
at its next Meeting. The initial budget 
planning was based on the advice of the 
officers of five groups of activities: engi- 
neering, conventions, publications, sustain- 
ing memberships, and general membership 
promotion. They were asked for their ad- 
vice for 1953 compared with 1952 and the 
three preceding years. Expense items 
which are policy-controlled were the sub- 
jects of study. 

Resignation of F. T. Bow ditch 

Mr. Bowditch had reported to the 
Society's President on June 13 that an 
emergency situation at National Carbon 
Company required his attention to new 
duties and his relinquishing the Society's 
Engineering Vice-Presidency. The Board 
regretfully accepted the resignation to be 
effective October 6 and appointed Henry J. 
Hood of Eastman Kodak to serve from 
October 6, 1952, through December 31, 
1953. Something of the scope of Mr. 
Bowditch's service to the Society is given 
later in this Journal under "Engineering 
Activities," and in the report opening this 
Journal. 



Nominations and Other Reports 

With one exception, the roster of nomi- 
nees for the Society's 1952 election was all 
cleared and was approved by the Board. 

For the first time in 36 years there has 
had to be a change in the nominee for 
Convention Vice-President. The Nomi- 
nating Committee had cause for pause: 
since 1916, the Society has had "Conven- 
tions by Bill Kunzmann" so the Com- 
mittee tossed into the lap of the Board the 
poser created by Bill Kunzmann's forth- 
coming retirement from National Carbon. 
The Board discussed at great length possi- 
bilities for revising the duties and lessening 
the travel and other demands made on the 
Convention Vice-President, but it was not 
possible within the long-established policies 
of the Society to work out a program that 
would enable Bill to accept the nomination. 
The Board, therefore, regretfully turned to 
the alternative of seeking another nominee 
and gave the job of finding someone to the 
Executive Vice-President and a committee 
of four. A number of suggestions were 
received and the final choice made was 
Jack Servies, Vice-President of National 
Theatre Supply. The nomination of Mr. 
Servies was approved by a letter ballot of 
the Board and his name completed the 
roster for the ballots which were mailed on 
August 25 to all voting members. 

Reports of the Fellow Award and other 
award committees were received and ap- 
proved. A complete account of awards 
will be given in a later Journal. Malcolm 
G. Townsley as chairman of a temporary 
committee to study the method of present- 
ing awards reported that his group favored 
making all the presentations at the ban- 
quet. An informal report from John G. 
Frayne, Chairman of the 75th (Spring of 
'53) Convention Planning Committee, 
briefly described the program, which is to 
be based on an historical theme, with the 
likely extra costs for such a project being 
partially offset by sales of a proposed book- 
let. Important developments in motion 
pictures and television over the past fifty 
years would be covered in several technical 
sessions, with particular papers covering 
the field from the beginning to the very 
latest along technical lines. 

Othe/reports approved were those of the 
Convention Vice-President, Editorial Vice- 
President and the three Section Chairmen. 



239 



Engineering Activities 



Engineering Vice-President 

Fred Bowditch, the Society's active and 
able Engineering Vice-President, has sub- 
mitted his resignation, effective October 
6, 1952. An increase in his responsibilities 
with National Carbon Go. no longer allows 
the time and attention that he feels the 
Engineering Vice-Presidency requires. 

Long active in the engineering and 
standards work of the Society, Fred was 
elected Engineering Vice-President for 
1950-52 and reelected for 1952-54. The 
diversity of his Society interests is indicated 
in the listing below, but this in no way 
begins to tell the story of the vital contri- 
butions he has made to the present healthy 
state of our engineering activities. 

Committee Period 

Color 1940-44 

Inter-Society Color Council 1940-52 

Papers 1941-44 

Progress 1941-45 

Screen Brightness 1 941 

Standards, Chairman 1940-47 1941-52 

Z22 (PH22), Chairman 1949-50 1946-52 



Television 
Board of Governors 
Nominations 
Fellow Award 



1947-49 
1949-52 
1949-52 
1950-52 



We know that through his continued 
membership on several of the above com- 
mittees he will maintain his close contact 
with the Society. 

His successor will be Henry Hood of 
Eastman Kodak. Henry started his com- 
mittee activity in 1945 as a member of 
the Non-Theatrical Equipment Com- 
mittee. This was reorganized in 1948 
as the Committee on 16mm and 8mm 
Motion Pictures with Henry as chairman. 
The committee blossomed under his 
leadership and in 1950 he was reappointed 
for a second two-year term, the maximum 
permitted by the Bylaws. At the con- 
clusion of his second term and in recogni- 
tion of his outstanding work, he was 
appointed Chairman of the Standards 
Committee. At the last meeting of the 
Board of Governors, July 17, Henry was 
appointed to complete the remainder of 
Fred's term of office. Henry Kogel, Staff 
Engineer. 



Atlantic Coast Section Regional Meeting at Atlanta 



The Regional Meeting of the SMPTE 
Atlantic Coast Section held on Friday, 
May 9, in Atlanta, Ga., as a joint endeavor 
with the Atlanta Section of the IRE and 
the Atlanta Chapter of the AIEE, attracted 
an attendance of over 200 in the Hightower 
Textile Building Auditorium of the Georgia 
Institute of Technology. The arrange- 
ments for the meeting were made by E. M. 
Stifle, Chairman of the Atlantic Coast 
Section, assisted by Charles D. Beeland and 
Ben Akerman, both of Atlanta. 
The program was : 

Comparison of Definition in Television and 
Photographic Processes by Otto H. Schade, 
Tube Dept., Radio Corporation of 
America, Harrison, N.J. 

Eastman Color Motion Picture Films by W. T. 
Hanson, Jr., Research Laboratories, 
Eastman Kodak Co., Rochester 4, N.Y. 

Synchro-Lite Powered 16mm Film Projector for 



Television by R. E. Putnam and E. H. 
Lederer, Broadcast Studio Engineering 
Sec., Electronics Div., General Electric 
Co., Syracuse, N.Y. 

Improved Television Film Reproduction by 
Vernon J. Duke and K. E. Mullenger, 
National Broadcasting Co., New York, 
presented by C. F. Daugherty, WSB-TV, 
Atlanta, Ga. 

Lighting for Television, a film, by courtesy of 
CBS-TV, New York, produced by Paul 
Wittig and directed by Lela Swift. 
Great interest was shown in this meeting. 
A number of requests have come in from 
persons who attended this meeting, asking 
for more similar meetings to be held in 
Atlanta. In addition to the large attend- 
ance from Georgia, engineers also came 
from the states of Alabama, Illinois, New 
Jersey, New York, South Carolina and 
Tennessee. E. M. Stifle, Eastman Kodak 
Co., 342 Madison Ave., New York 17, N.Y. 



240 



Letters to the Editor 



Re: Stereoptics Ltd. Cameras for Telecinema Film 



My attention has been drawn to the 
article by Mr. R. Spottiswoode which ap- 
pears in the April 1952 Journal. 

In order to correct any misunderstanding 
which may, perhaps, have arisen in the 
minds of some readers, I would like to draw 
attention to the following points which Mr. 
Spottiswoode no doubt unintentionally 
has omitted to mention. 

The principle of the stereo photographic 
equipment, embodying two cameras, sup- 
plied for the production of stereo films for 
the Festival of Britain Telecinema, was de- 
vised by the undersigned and the apparatus 
was supplied by one of my Companies 
Messrs . Stereoptics Ltd . of London . More- 
over, the principle involved is the subject of 
British Complete Patent Application No. 
17,086/50 which, it is understood, is due for 
acceptance at an early date. 

A full description of the apparatus was 
given in my paper "Stereoscopy in the 
Telekinema and in the Future" which I 
produced last year at the request of the 
British Kinematograph Society and which 
was published in that Society's Journal, 



British Kinematography, 18: pp. 172-181, No. 
6, June 1952. 

June 17, 1952 L. Dudley, Director 
Stereoptics, Ltd. 
Odeon Theatre 
263 Kensington High St., 
London, W. 8, England 

Note by Raymond Spottiswoode 

One out of the four Telecinema pictures, 
A Solid Explanation, was shot with the aid of 
two film cameras of well-known make, 
mounted on a special base incorporating 
the patent Mr. Dudley refers to and de- 
signed and built under his company's 
direction. This film carries the credit 
title, "The equipment, incorporating 
cameras by Newman and Sinclair, Ltd., 
was developed by Stereoptics, Ltd." 



July 12, 1952 



Raymond Spottiswoode 

Kingsgate 

Sudbury Hill 

Harrow-on-the-Hill 

England 



Book Reviews 



Classrooms 

No. 1 in a series, Planning Schools for Use of 
Audio-Visual Materials. Published (1952) 
by Department of Audio-Visual Instruc- 
tion, National Education Association, 1201 
Sixteenth St., N.W., Washington, D.C. 
40 pp. 20 illus. Paper covered. 6X9 
in. Price $1.00. 

This is the first of a series of booklets on 
planning schools for the use of audio-visual 
aids. 1 Devoted entirely to the planning of 
classrooms for greatest efficiency, it is pre- 
pared as a guide to architects and other 
planners who are designing new schools or 
remodeling old classrooms. Various plan- 
ning groups and manufacturers of audio- 
visual materials collaborated in preparing 
the text. 

1 D. F. Lyman, "Audio-Visual Instruction Con- 
ference," Jour. SMPTE, 58: 445-449, May 1952. 



The introduction states that it is gen- 
erally recognized that the use of audio- 
visual materials greatly enriches the child's 
classroom education. Thus it prepares 
him better to meet the demands of the 
modern world. But it is not so well recog- 
nized that school buildings must be planned 
carefully by administrators, architects, 
faculties, patrons and builders, or the 
audio-visual program will be quite in- 
effective if not impossible. The classroom 
is considered in this first study because it is 
the first and most important part of the 
building to equip properly. 

By far the chief function of the book is to 
describe methods of darkening the class- 
room to insure good tonal quality in the 
projected picture. Several ways of darken- 
ing the room are described : drapes, opaque 
shades, Venetian blinds, louvres and jal- 
ousies. Drawings and photographs of 



241 



actual installations clarify the text. Of 
great practical value is the list of 36 com- 
panies that produce or distribute materials 
for this purpose. 

One short section describes the require- 
ments for adequate ventilation of the dark- 
ened classroom. Other sections show the 
proper ways to select, mount and use the 
projection screen. There are specifica- 
tions for projection stands, placement of 
loudspeakers, switches, receptacles, and 
conduits to connect the classroom with the 
central sound and television system. A 
brief section on acoustics states the funda- 
mental problems simply and clearly, with 
references to other authorities for more de- 
tailed information. 

Specifications for display facilities and 
project areas for small groups emphasize 
the importance of considering other audio- 
visual aids. Another short section deals 
with facilities for storing equipment. One 
of the appealing characteristics of this 
booklet is that it describes in broad terms 
the general requirements for good results 
and the best methods of obtaining them 
but does not go into burdensome detail. 

The final section describes the steps re- 
quired to achieve the goals previously out- 
lined, focusing the attention of all planners 
on the activities for which provision should 
be made, and getting all to support the 
program. Teachers, particularly, should 
be consulted. A final paragraph invites 
comments from readers who need more in- 
formation or have additional ideas to share 
with others. A bibliography cites 26 
articles and books on subjects relating to 
this problem. 

In view of the large number of schools 
now being planned or remodeled, and in 
view of the demonstrated need for a better 
understanding of the requirements for 
audio-visual aids, this booklet should be 
given immediate, wide circulation among 
those who plan classrooms. D. F. Lyman, 
Development Dept., Camera Works, East- 
man Kodak Co., Rochester 4, N.Y. 

Proceedings of the London Confer- 
ence on Optical Instruments 1950 

(Held at Imperial College, London, July 
1950.) Published (1952) by John Wiley 
& Sons, 440 Fourth Ave., New York 16. 
i-xv + 256 pp. + 8 pp. index. 100 illus. 
5 X 8 in. Price $7.00. 



Kingslake reviews recent developments 
in photographic lenses under high index 
glasses, double-, triple- and four-element 
systems, high aperture, Petzval types, 
wide angle, telephoto, afocal, zoom, 
catadioptric system, increased depth of 
field, aspheric surfaces, mechanical im- 
provements and other materials. Over 
170 patents, not counting duplicates in 
other countries, have issued on photo- 
graphic lenses since 1940. H. H. Hopkins 
discusses the zoom lenses as symmetrical 
systems of variable power. Improvements 
possible in high aperture lenses having 
spherical fields (curved film) are discussed 
by Warmisham. The remaining five-sixths 
of the report covers reflecting microscopes, 
gratings and their instruments, phase 
microscopes, spectrophotometers, reflect- 
ing telescopes, miscellaneous (velocity of 
light and measurement of distance; pho- 
tometry of optical instruments), and new 
optical materials. This is a good summary 
of the status in 1950 and gives a fairly 
complete coverage in a small space. The 
references provided will meet the imme- 
diate need for more detail in each field. 
Progress has come mainly from the newer 
glasses of high index and lower dispersions 
allowing the designer to use simpler con- 
structions, although a few items reveal 
progress from human ingenuity. 0. W. 
Richards, American Optical Company, 
Stamford, Conn. 

Technical Optics (Vol. II) 

By L. C. Martin. Published (1950) by 
Pitman, 2 W. 45 St., New York 19. 327 
pp. + 12 pp. appendix + 4 pp. index. 
Approx. 260 illus. 5| X 8^ in. Price 

$7.50. 

Like most books on technical optics 
this volume follows the regular pattern, 
having one chapter on single lenses and 
magnifiers followed by a chapter each for 
telescopes, magnifiers, photographic lenses, 
and the testing of optical instruments. 
In each chapter the historical development 
is followed by some of the technical ques- 
tions encountered in the design of optical 
instruments. 

Related topics are the subject of chapters 
on binocular vision and binocular instru- 
ments, photometry (where projection sys- 
tems and projectors are briefly described), 



242 



and aspheric surfaces. In the latter 
chapter, Schmidt systems and other recent 
high-speed aspheric systems which are of 
interest to the projection of television 
images are discussed. In four appendixes, 
symbols, defraction gratings, chromatic 
abberation of thin lenses, and data on 
seven photographic lenses are given. 

The publisher states, "the book is of the 
greatest value to scientific instrument 
makers, ophthalmic opticians, spectacle 
makers, and students." The technical 
descriptions and derivations do not make 
this book easy to read for the casual 
reader but rather a book for the student 
and scientific user of optical instruments. 
Even though it can serve as a useful ref- 
erence or study book of technical optics 
it cannot be classified as a treatise on the 
subject. A great majority of the references 
are to British works and authors, and little 
mention is made of work done in other 
countries. 

Engineers and physicists dealing with 
the design of optical instruments will 
find this book a valuable addition to their 
library. Other American readers who 
want an insight into this branch will, 
no doubt, prefer Fundamentals of Optical 
Engineering by D. H. Jacobs, or The 
Principles of Optics by A. G. Hardy and 
F. H. Perrin. Dr. John L. Maultbesch, 
Vice-President, Kollmorgen Optical Corp., 
347 King St., Northampton, Mass. 

Focal Cine books 

A special series of inexpensive, popular 
monographs on motion picture subjects, 
consisting of the following : 
How to Script, by Oswell Blakeston, 1st ed., 

1949 

How to Film, by G. Wain, 3d ed., 1952 
How to Direct, by Tony Rose, 1st ed., 1949 
How to Edit, by H. Baddeley, 1st ed., 1951 



How to Act, by Tony Rose and Martin 

Benson, 1st ed., 1951 
How to Process, by Leslie J. Wheeler, 1st ed., 

1950 

How to Title, by L. F. Minter, 1st ed., 1949 
How to Project, by Norman Jenkins, 2d ed., 

1951 
How to Cartoon, by John Halas and Bob 

Privett, 1st ed., 1951 
How to Use 9.5mm, by D. M. Neale, 1st ed., 

1951 

Published by Focal Press Ltd., 31 
Fitzroy Sq., London, W. 1, England. 
Paper bound. Price 7s. 6d. 

This series of popular monographs is, 
in a sense, the motion picture counterpart 
to Focal Press' famous series of basic 
booklets in still photography. However, 
for the "still" series the titles were char- 
acterized by the two-word prefix "All 
About" instead of "How to," as in the 
present series. The general level of the 
motion picture booklets is considerably 
more advanced than that established for 
the still booklets; nevertheless, by no 
stretch of the imagination can the motion 
picture booklets be recommended to the 
specialist, except possibly to the extent 
that a specialist in one field might find 
the booklets on subjects outside his re- 
spective field worth reading. For example, 
a director or film editor could derive some 
insight into the complexities of processing 
by a reading of How to Process. But he 
would gain a false impression of modern 
motion picture laboratory practice if he 
went no further, for the booklet treats 
the subject entirely from a standpoint of 
home processing on old-fashioned drums. 

The booklets generally are well written 
and thoroughly illustrated. They are 
obviously directed to the serious amateur 
who wants to improve his film results and 
dabble in home laboratory procedures. 
Lloyd E. Varden, Pavelle Color, Inc., 533 
W. 57 St., New York 19, N.Y. 



SMPTE Officers and Committees: The roster of Society Officers and the 
Committee Chairmen and Members were published in the April Journal. 



243 



Positions Wanted 



Production, TV or Motion Picture: NYU BA in motion picture and TV production; 
participated in productions as director and unit mgr; experience as motion picture 
sensitometrist ; at present motion picture negative assembler and cutter; worked swing 
shift while attending college; licensed 35mm projectionist; single, 29, veteran, resume 
on request; go anywhere. Harold Bernard, 560 Eastern Pkwy, Brooklyn 25, N.Y. 

TV Producer-Director: Now Chief of Production in Army's first mobile TV system; 
military experience in writing-directing high-speed, low-cost instructional productions; 
formerly TV producer-director, KRON-TV San Francisco, five shows weekly; will be 
separated from service Nov. 1952; desire connection in educational TV, preferably em- 
ploying kinescope techniques; married; prefer West Coast, but willing to travel; resume, 
script samples, pictures of work on request; 1st Lt. Robert Lownsbery, SigC Mbl TV 
Sys, c/o Sig Photo Center, 35-11 35th Ave., Long Island City 1, N.Y. 

Journals Available and Wanted 

Available 

Upon a reasonable offer to Alfred S. Norbury, 3526 Harrison St., Kansas City 3, Mo.: 
Vol. 44 (Jan.-June 1945) Vol. 50 (Jan.-June 1948) 

Vol. 45 (July-Dec. 1945) Vol. 51 (July-Dec. 1948) 

Vol. 47 guly-Dec. 1946) Vol. 52 (Jan.-June 1949) 

Vol. 48 (Jan.-June 1947) Vol. 56 (Jan.-June 1951) 

Vol. 49 (July-Dec. 1947) Vol. 57 (July-Dec. 1951) 

A set of Journals from January 1945 through 1951 at SI 5. 00 plus packing and carrying 
costs from Richard W. Maedler, 32-52 46 St., Long Island City 3, N.Y. 

Complete set, in excellent condition, from January 1930 to date, plus one issue of Sep. 
tember 1928 from Don Canady, 5125 Myerdale Drive, R.R. 15, Cincinnati, 36, Ohio. 

5 years (1947-51) in perfect condition plus the indexes for 1936-45 and 1946-50 and 
including the 1949 High-Speed Photography, upon any reasonable offer to Vic Gretz- 
inger, 3547 Suter St., Oakland 19, Calif. 

Transactions Nos. 11, 14, 20, 21, 23, 25, 27, 28 and 38; and 22 years of the Journal (1930- 
1951) except for Jan., Feb., Mar. and Apr. of 1934, Jan. and Apr. of 1948, and Feb. 1950; 
also these extra single copies Nov. 1930; Jan., Feb., July and Nov. 1931 ; June 1932; 
Mar. and Apr. 1933; Dec. 1934; Jan. and May 1935; Oct. 1938; July and Dec. 1940; 
Oct. 1948 and Jan. 1950, upon any reasonable offer made to Paul J. Larsen, Assistant to 
the President, Borg-Warner Corp., 310 So. Michigan Ave., Chicago 4, 111. 

Wanted 

Transactions 1, 6 and 7. Contact Mrs. Dorothy Gelatt, Henry M. Lester, 101 Park Ave., 
New York 17, N.Y. 

High-Speed Photography, Volume 7, reprint or original Journal, March 1949, Part II, by 
John H. Waddell, Wollensak Optical Co., 850 Hudson Ave., Rochester 21, N.Y. 

244 



New Members 



The following members have been added to the Society's rolls since those last published. The 
designations of grades are the same as those used in the 1952 MEMBERSHIP DIRECTORY. 



Honorary (H) 



Fellow (F) 



Active (M) 



Associate (A) 



Student (S) 



Barker, Lovell H., Film Processing Laboratory 

Owner. Mail: 9208 Memorial, Detroit 28, 

Mich. (M) 
Bernstein, Paul, TV Studio Technician and 

Engineer, WOI-TV, Iowa State College, 

Ames, Iowa. (A) 
Blanchard, Vernon W., Chemist, E. I. Du Pont 

de Nemours & Co., Photo Products Dept. 

Mail: 42 South Drive, Lawrence Brook 

Manor, Rt. 9, New Brunswick, N.J. (A) 
Bostwick, James W., Manager, Motion Pictures 

& Slide Films, General Motors Photographic, 

General Motors Corp., B-120 GM Bldg., 

Detroit 2, Mich. (M) 
Brasier, C. S., Scientific Photographer, Ministry 

of Supply, British Government. Mail: 4 

Romney Rd., Southcourt, Aylesbury, Bucks, 

England. (A) 
Carter, Bryan, Chief Electrician, Universal 

Pictures Co., Universal City, Calif. (M) 
Chessman, Walter E., Jr., Mechanical Engineer, 

Alexander Film Co. Mail: 1516 Vista PL, 

Colorado Springs, Col. (A) 
Coan, Edward M., Television Engineer, Allen 

B. DuMont Laboratories, Inc. Mail: 37 

Overlook Rd., Cedar Grove, N.J. (M) 
Cook, George R., Treasurer, Radio Station 

WLS. Mail: 1419 Lathrop Ave., River 

Forest, 111. (M) 

Cotcher, Alfred L., Electronic Scientist, Na- 
tional Bureau of Standards. Mail: 3410 

Highview Ct., Wheaton, Md. (A) 
Dobbs, Frank S., Manufacturer, Cine Products 

Supply Corp., Ashland, N.J. (M) 
Drucker, Donald, Motion Picture Film Editor, 

Charles R. Sene. Mail: 680418 Ave., 

Brooklyn, N.Y. (A) 
Faithorn, Nathaniel R., Television Engineer, 

The Associated Broadcasters, Inc. Mail: 

430 Myra Way, San Francisco 16, Calif. 

(A) 
Filmer, Philip, General Manager, General 

Motors Photographic, General Motors Corp., 

407 General Motors Research Bldg., Detroit, 

Mich. (M) 
Green, Phil C., Television Engineer, WSM 

Television. Mail: 4112 Rockdale Ave., 

Nashville, Tenn. (A) 

Hewins, Leonard J., Manager, Mole-Richard- 
son (Spain). Mail: Garcia Morato 121, 

Madrid, Spain. (M) 
Huffman, Robert L., Mechanical Engineer, 

Automatic Electric Co. Mail: 1033 W. 

Van Buren St., Chicago 7, 111. (A) 
Karo, James, Photographic Supervisor, Sandia 

Corp. Mail: 1123 Silver Ave., S.W., 

Albuquerque, N.M. (A) 



Keller, John S., Supervisor, Field Optical 
Installations, Sandia Corp. Mail: San 
Felipe Lodge, Apt. 201, Sal ton Sea Base, 
Westmorland, Calif. (M) 

Koch, William A., Chemist, Eastman Kodak 
Co., 342 Madison Ave., New York 17, N.Y. 
(M) 

Lenz, Irvin W., High-Speed Motion Picture 
Camera Technician, Sandia Corp., Field 
Test Dept., Sandia Base, Albuquerque, N.M. 
(A) 

Macauley, Alan C., 16mm Production and Dis- 
tribution, World Films. Mail: Box 72, 
Sierra Madre, Calif. (A) 

Marcus, Paul, Chief Engineer, Partner, Bell 
Recording Co., 112 W. 89 St., New York 
24, N.Y. (A) 

Matt, Richard J., Producer, Box 581, Fond du 
Lac, Wis. (M) 

McNaughten, Neal, Director of Engineering, 
National Association of Radio and Television 
Broadcasters, 1771 "N" St., N.W., Wash- 
ington 6, D.C. (M) 

Moore, Charles S., Supervisor of Sound Engi- 
neers, Radio Corporation of America. Mail: 
6703 Starling Cir., Dallas, Tex. (A) 

Pendreigh, Harold A., Projectionist, J. Kelly 
and R. Pannett. Mail: 88 George St., 
Rockhampton, Queensland, Australia. (A) 

Peterson, Harry, Cinematographer, Atlas Film 
Corp. Mail: 411 Marion St., N., Oak Park, 
111. (M) 

Rafalon, Jules, Mechanical Engineer, Assistant 
Chief, Pathe Laboratories, Inc., 105 E. 106 
St., New York 29, N. Y. (M) 

Read, Edmond C., Jr., Kinescope Recording 
Engineer, National Broadcasting Co. Mail: 
4038 Michael Ave., Venice, Calif. (M) 

Reiter, Samuel S., New York University. Mail: 
1937 E. 37 St., Brooklyn 34, N.Y. (S) 

Richardson, Robert W., Motion Picture Writer, 
Photographer and Producer, Barber-Greene 
Co., 400 Highland Ave., Aurora, 111. (M) 

Rowe, Thomas L., Chief Engineer, Radio 
Station WLS. Mail: 2324 W. Lunt, Chicago 
45, 111. (M) 

Ruberg, Elden E., Sound Technician, Radio 
Corporation of America. Mail: 1039 Hart- 
zell St., Pacific Palisades, Los Angeles, Calif. 
(A) 

Strauch, Frederic P., Jr., Sales Engineer, Bell & 
Howell Co. Mail: 1122 Dartmouth, Wil- 
mette, 111. (A) 

Wilner, John, Director of Engineering, Hearst 
Corp., 2610 N. Charles St., Baltimore 18, 
Md. (A) 



245 



Wilson, Ralph J., Supervisor, Photo Section, 
Sandia Corp. Mail: 295 C St., Brawley, 
Calif. (A) 

Winkler, Edward A., Chemical Engineer, 
Eastman Kodak Co., 342 Madison Ave., 
New York 17, N.Y. (M) 

Wolf, George E., Assistant Production Manager, 
Murphy-Lillis Productions, Inc. Mail: 3 
Glenwood St., Little Neck, L.I., N.Y. (A) 

Wood, Donald M., In Charge of Research 
Photography, Bendix Aviation Corp. Mail: 
10410 E. Jefferson, Detroit 14, Mich. (A) 



Zaccardi, Sgt. Carmie M., Motion Picture 

Photographer, U.S. Air Force, Box 494, Hq. 

AFFTC, Edwards Air Force Base, Edwards, 

Calif. (A) 
Zost, Elmer G., Chemist, Alexander Film Co., 

Alexander Film Bldg., Colorado Springs, Col. 

(A) 

CHANGES IN GRADE 
Drew, R. O., (A) to (M) 
Foster, John C., (A) to (M) 
Gawel, Eugene W., (S) to (A) 
Paramasivaiah, P., (S) to (A) 



Current Literature 



The Editors present for convenient reference a list of articles dealing with subjects cognate 
to motion picture engineering published in a number of selected journals. Photostatic 
or microfilm copies of articles in magazines that are available may be obtained from The 
Library of Congress, Washington, D.C., or from the New York Public Library, New 
York, N.Y., at prevailing rates. 



American Cinematographer 

vol. 33, June 1952 
Economy Set Lighting With Gone Lights 

(p. 248) 

Camera Heater for Cold-weather Filming 
(p. 250) R. Lawton 

vol. 33, July 1952 

Stereo Movies Without Spectacles (p. 295) 

A. D. Roe 

Filters in Cinematography (p. 296) /. Forbes 
Electronic-Photo Recording New TV 

Filming Method (p. 298) C. L. Anderson 

Bild und Ton 

vol. 5, May 1952 
Die transportable Riffelwand (p. 150) G. 

Hoffmann 
Warum zerspringen Stufenlinsen? (p. 136) 

H. Jent&ch 
Mikrofotografie im Dienste der Kreislauf- 

forschung (p. 139) G. Vogel 

British Kinematography 

vol. 20, May 1952 

Problems of Storing Film for Archive Pur- 
poses (p. 150) H. G. Brown 

Electronic Engineering 

vol. 24, July 1952 

Some Converter Tubes and Their Applica- 
tions (p. 302) /. A. Jenkins and R. A. 
Chippendale 

A Method of Measuring Television Picture 
Detail (p. 308) G. G. Gouriet 

Electronics 

vol. 25, June 1952 

Pack-Carried Television Station (p. 98) 
L. E. Flory, W. S. Pike, J. E. Dilley and 
J. Af. M organ 



Self-Focusing Picture Tube (p. 107) A. T. 
Bentley, K. A. Hoagland and H. W. Gross- 
bohlin 

Kino-Technik 

no. 5, May 1952 
Deutsche Ausfuhr von Kino-Film rollt 

langsam an (p. 101) 
Geiselgasteig ist fur den Farbfilm geriistet 

(p. 102) 
Das Bild der deutschen Filmwirtschaft 

gestern und heute (p. 105) A. N, Narath 
Welche Anforderungen stellt das Fernsehen 

an den Rohfilm? (p. 114) 
Storungen bei der Vorfuhrung von Farb- 

filmen (p. 117) K. Braune and H. Tummel 
no. 6, June 1952 

Welche Anforderungen stellt das Fernsehen 

an den Rohfilm? (p. 149) 
Storungen bei der Vorfiihrung von Farb- 

filmen (p. 151) K. Braune and H. Tilmme 

Radio & Television News 

vol. 47, June 1952 

(Radio-Electronic Engineering Section) 
What's Ahead for Small-Town Television? 

(p. 31) N. Sklarewitz 

Radio & Television News 

vol. 48, July 1952 
Improved Intercarrier Sound System (p. 

36) W. H. Buchsbaum 
Unique Magnetic-Tape Applications (p. 

38) L. A. Wortman 
Pulses in Sound Reproduction (p. 59) G. 

Southworth 

Tele-Tech 

vol. 11, Aug. 1952 
Eidophor Projector for Theatre TV (p. 1 12) 



246 



New Products 



Further information about these items can be obtained direct from the addresses given. 
As in the case of technical papers, the Society is not responsible for manufacturers' state- 
ments, and publication of these items does not constitute endorsement of the products, 




Movie Sound 8 is the first commercially 
available equipment for recording and 
reproducing magnetic sound on 8mm film. 
The equipment comes in a single case, 
including a built-in 6-in. speaker and a 
microphone, and is marketed at $398.50 
by Movie Mite Corp., 1105 Truman Rd., 
Kansas City 6, Mo. Magnetic striping 
of 8mm film is now available at 3^ a foot 
from Reeves Sounder aft Corp., 10 E. 
52 St., New York 22, N.Y. 

Movie Mite Corp. felt that an entirely 
new projector should be designed to get 
sound successfully on 8mm, chiefly to 
overcome wow and flutter problems and 
to provide 24 frame/sec sound speed and 
also the old, silent speed. To avoid 
sprocket hole modulation, a system called 



the Roto-Magnetic Stabilizer was de- 
veloped to allow scanning the film in a 
flat plane. The use of a slightly tapered 
sound drum provides a substantial amount 
of the edge guiding needed. There are 
only two sprockets. They are driven by 
a worm gear connected by a rubber belt 
to the motor. 

The standard projector has two input 
positions for the record player and for 
the microphone. A small mixer is avail- 
able for the operator who wishes to record 
from two records and a microphone. It 
is not necessary to use special film stock. 
Old 8mm films as well as new can be given 
the 25-mil magnetic stripe which is placed 
outside the perforations. 



247 




New electronic humidity controls are de- 
scribed in .Bulletin F-5173 recently issued 
by Barber-Colman Co., Rockford, 111. It 
is called two-position and proportioning for 
process or comfort control. It is a plug-in 
element designed for wide range with simple 
adjustments. In spaces supplied by a cen- 
tral fan, the sensing element is mounted 
either in the duct or the conditioned space, 
remote from the amplifier and adjustments. 
For controlling humidity in spaces not com- 
pletely air conditioned, the control is avail- 
able with the operating adjustment mech- 
anism mounted in a cabinet. 



Nema Movie Guide 1952 is a com- 
pilation of complete data on "16mm Elec- 
trical Films." The Guide covers 409 films 
giving running time, color, sales or rental 
prices, release dates when ascertainable, 
sources (producer or chief distributor, with 
other possibilities covered in an extensive 
index of producers and distributors), and 
grading of films when that was obtainable, 
with keys for: guide or manual; primary; 
elementary; junior high school; senior 



high school; college; trade school and 
trade; and adult education. A 6-page 
"Classification by Subjects" makes this 
Guide very useful. It should be noted 
that there is only one film distributed by 
NEMA Installing Armored Cable. All the 
other 408 films must be ordered from the 
sources listed. The Nema Movie Guide is 
available from the National Electrical 
Manufacturers Association, 155 E. 44 St., 
New York 17, N.Y. 



Meetings 



72d Semiannual Convention of the SMPTE, Oct. 6-10, Hotel Statler, 

Washington, D. C. 

Other Societies 

National Electronics Conference. Annual Meeting, Sept. 29-Oct. 1, Sherman Hotel, 

Chicago, 111. 

Optical Society of America, Oct. 9-11, Hotel Statler, Boston, Mass. 

American Institute of Electrical Engineers, Fall General Meeting, Oct. 13-17, New 

Orleans, La. 

American Physical Society, Oct. 17-18, Cornell University, Ithaca, New York 
Acoustical Society of America, Nov. 13-15, Balboa Park, San Diego, Calif. 
American Standards Association, Annual Meeting, Nov. 19, Waldorf-Astoria, New York 
American Physical Society, Nov. 28-29, Washington University, St. Louis, Mo. 
American Institute of Chemical Engineers, Annual Meeting, Dec. 7-10, Cleveland, Ohio 
Institute of Radio Engineers Conference and Electronics Show, 5th Annual Southwestern 

Conference and Show, Feb. 5-7, San Antonio, Texas 



248 



Basic Principles of the 
Three-Dimensional Film 



By RAYMOND SPOTTISWOODE, N. L. SPOTTISWOODE and 
CHARLES SMITH 



Professional three-dimensional (3-D) film productions cannot be satisfactorily 
undertaken without a comprehensive theory of the transmission of an image 
in space from scene to screen. In Part I the outlines of such a theory are 
laid down, and the elements of a standard set of concepts and nomenclature 
put forward. Part II draws an example from a recent film, The Black Swan, to 
show how the stereotechnician computes a sequence of shots in the desired 
space relationship, and how simple graphical techniques may be employed to 
plot such relationships. From these graphs may be determined the magnitude 
of any postcorrections required to alter the continuity in space, to adjust 
the film to screens of widely differing size or to eliminate certain camera 
errors. Part III forms a critique of existing camera procedures, including 
those based on the supposed identity between human vision and the viewing 
of the space image. Part IV sums up the differences of technique between 
the flat film and the 3-D film. 



u, 



p TO NOW the production of three- 
dimensional (3-D) films has been spo- 
radic scattered all over the world and 
separated by long intervals of time. 
Most of the practical information avail- 
able was to be found in papers by the 
American pioneer, J. A. Norling, which 
were read before the Society; 1 but these 
dated from before World War II and 
applied to films of rather limited scope. 

A contribution submitted July 21, 1952, by 
Raymond Spottiswoode, N. L. Spottis- 
woode and Charles Smith, Stereo Tech- 
niques, Ltd., 36, Soho Square, London, 
W.I., England. This article is an adap- 
tation of part of the forthcoming book, The 
Theory of Stereoscopic Transmission.* 



More recently in England, the Festival of 
Britain afforded an opportunity to pro- 
duce a varied program of stereoscopic 
films; these too have been described in 
outline in the Journal. 2 ' 3 Production did 
not stop at this point, however, for a fur- 
ther series of films was initiated for com- 
mercial distribution starting in the early 
summer of 1952. Both these programs 
were based on the same body of technical 
principles: both were the work of the 
same groups, one in Canada for the ani- 
mation films, the other in Britain for the 
studio and actuality films. By the com- 
pletion of the second program, therefore, 
with an output of about a dozen films, 
much production experience had been 



October 1952 Journal of the SMPTE Vol. 59 



249 



gained and knowledge accumulated on 
the ways in which audiences see and react 
to this new kind of film. The present 
paper is an attempt to summarize a part 
of this knowledge in the hope that it may 
be of value to American producers who 
are experimenting in the 3-D medium. 
To make the theoretical part of the treat- 
ment more concrete, we relate it in an 
extended example to a particular film 
completed a few months ago. 

A 3-D Ballet Film 

The presentation of our Festival pro- 
gram at the Telecinema drew many re- 
quests for a stereoscopic ballet a sub- 
ject notoriously difficult to film satis- 
factorily in the ordinary way. We 
therefore decided to produce a ballet 
film for 1952, even though time did not 
allow of special choreography to take 
fullest advantage of the dimension of 
depth. Our final choice fell on an epi- 
sode from Tschaikovsky's Swan Lake, 
which made a story complete in itself 
within the limits of 13 minutes of film, 
and enabled us to feature two of the star 
dancers of the Sadlers Wells and Covent 
Garden companies, Beryl Grey and John 
Field. 

Shooting was to be limited to four days 
on the studio floor, and this meant careful 
preplanning of stereoscopic effects in rela- 
tion to the script. For this purpose it 
was essential to know how the dancers 
were to move in relation to the move- 
ments of the camera, which was to be 
mounted on a crane in the interests of 
complete fluidity. There was, however, 
a formidable problem to contend with 



which has no counterpart in the making 
of ordinary films : namely, to control the 
position in space in the ultimate movie 
theater of each scene occurring in space 
before the camera. The continuity 
might demand a smooth spatial transi- 
tion between one shot and the next; or 
there might have to be an abrupt impact 
of something presented much nearer to 
the eye or much farther away than the 
audience would expect. Examples of 
both types of "continuity in space" 
abound in this film. Again, from shot 
to shot it would be necessary to adjust 
the camera to the precise range of dis- 
tances in the scene before it; and if any 
errors occurred at this stage, it must be 
possible to determine and correct them 
by optical printing. Finally, in thel 
interests of strain-free viewing, it was 
essential to be able to take into account 
all those factors which affect the fusion 
of the images, and whose neglect in the 
past has often led to eye fatigue and has 
tended to give 3-D films a bad name 
among the public. 

There is no way of achieving thisj 
assured control over the image through- 
out its progress to the movie theater ex- 
cept by having at one's command a com- 
plete knowledge of the stereo transmis- 
sion system between camera and specta- 
tor. Fortunately, long before the shoot- 
ing of The Black Swan was attempted, 
such a transmission theory had been 
worked out, and a full account of it will 
shortly be available to American readers. 4 
Nonetheless, some attempt must be made] 
here to indicate the nature of the pro 
lems and the lines along which they ca 
be solved. 



PART I: THEORY 



As is well known, all commercial 
stereoscopic film systems of today are of 
a type which may be called piano-stereo- 
scopic: that is, the constituent optical 
images from which the depth image is 
formed by binocular fusion are projected 
on a surface, the screen. In large-screen 



projection, these optical images a 
superimposed, and must be sorted out byj 
each spectator with the aid of individual! 
viewing devices, which are normally of! 
polarizing material. It is thus necessarw 
to start with an analysis of the way tha 
spectator sees' the picture in space, after! 



250 



October 1952 Journal of the SMPTE Vol. 59 



which we can work back through the pro- 
jection and production processes to the 
camera which is to be controlled on the 
studio floor. 

Psychological Viewing Factors 

In the spectator's mind two altogether 
different sets of impulses are at work. 
The binocular faculty attempts to place 
objects in space by methods which are 
still imperfectly understood in their en- 
tirety, but which may for simplicity be 
likened to the working of a rangefinder. 
At the same time, other departments of 
the mind are busy observing all sorts of 
other clues to depth and position in space. 
There may well arise conditions when 
these two sets of data will conflict, lead- 
ing to an ambiguity in the image which 
different people will resolve differently 
much as two people may sit down before 
a Picasso canvas in the Museum of 
Modern Art and come to wholly differ- 
ent conclusions as to what it is all about. 
Even more serious difficulties will arise 
if the conflict is so fundamental that the 
spectator cannot bring himself to believe 
in the stereoscopic data. A scene may 
be brought forward to a certain plane in 
space, but will not in fact appear to be 
there because the audience cannot accept 
the fact that a dining room table or a 
ballet dancer is poised in space over the 
front rows of the stalls. This effect has 
been known for many years, and is well 
analyzed in a classic paper by Professor 
J. T. 



T 
does 




The planning of our stereoscopic films 
of course take account of these and 
many other psychological factors; and 
hope, if interest in the 3-D film con- 
active, to discuss in a later paper a 
mber of new ways of bridging the re- 
maining gap between audience and space 
film. In the present paper we shall con- 
fine ourselves to considering the physical 
elements in the stereoscopic transmission 
system, since these have been the subject 
of much fruitless debate, which it is time 
to try and replace with an agreed nomen- 



clature and method of mathematical 
approach. 

The Mechanics of Viewing 

The elements of a piano-stereoscopic 
projection system, with image separation 
at the spectators' eyes, are sketched in 
Fig. 1. A generalized spectator is 
shown, placed at a distance, V, from the 
screen, onto which have been thrown 
left- and right-eye images. It is con- 
venient to consider these images as con- 
sisting of a multitude of separate points, 
much as is often done in discussions of 
film resolving power. In general, to 
each point on the left-eye image there 
will be some corresponding point in the 
right-eye image, both image points hav- 
ing the characteristic that they represent 
the same object point in the original 
scene.* These image points are some- 
times called homologous points, and they 
are represented in Fig. 1 by L and .ft.f 

The eyes are shown as having a sepa- 
ration, t, this letter also being used in our 
nomenclature to denote the lateral sepa- 
ration of optical axes, suitable subscripts 
being used to distinguish the camera and 
projector. Through their selecting 
viewers, the eyes regard separately the 
left and right members of each pair of 
homologous points on the screen, whose 
horizontal separation is known as paral- 
lax. Parallaxes are always denoted by 

* Note that the original object may be 
imaginary, as in 3-D abstract and cartoon 
films. 

f It is noteworthy that, in a projection sys- 
tem such as we are discussing, the eyes are 
able to prompt the mind without any addi- 
tional clues as to which pairs of points are 
to be considered homologous; occasional 
errors as in the fusion of wire mesh and 
wallpaper patterns occur also in bin- 
ocular vision and are of negligible impor- 
tance in practice. On the other hand, 
some types of integral screen, which dis- 
pense with viewers for seeing 3-D films, re- 
quire the transmission of information as to 
which points are homologous, and are 
therefore "information-consuming" and 
wasteful. 



Spottiswoode, Spottiswoode and Smith: 3-D Photography 



251 



Screen 




L and R are homologous 
image points delivered 
at screen by projector(s). 



Image-selecting 
viewers 



Fig. 1. Construction of a space image point (/) from 
optical image points, L and R. A spectator's eyes, EL, 
E R , having a lateral separation, t, are equipped with 
selecting viewers and regard, respectively, left and right 
corresponding image points, L and R. These are separated 
on the screen by a parallax, z s , which may be positive or 
negative. The spectator, distant Ffrom the screen, will see 
the fused image point, 7, at the intersection of the rays from 
E L to L, and E R to R. His distance from / is denoted by P. 



the letter z, a subscript being added to 
distinguish the kind of parallax referred 
to. Thus a screen parallax is z s , a paral- 
lax on the projected film z p , a parallax 
introduced by displacement in the optical 
printer z d , and a parallax originating in 
the camera z c . 

Three special cases are shown in Fig. 1 ; 
(a) that in which z s = t, for which rays 
of light are reflected parallel from the 
screen, so that the image point is placed 
at infinity; (b) that in which z t = 0, in 



which the point is imaged in the plai 
of the screen (whence it follows that a 
normal flat film is merely a special case 
of the 3-D film, that in which z s = for 
all image points) ; and (c) that in which 
z g = t, and the image, as may be seen 
from simple geometry, is halfway out to 
the spectator. 

From previous theoretical discussion, 
the impression has got around that stereo- 
scopic projection is extremely compli- 
cated, requiring special and often vari- 



252 



October 1952 Journal of the SMPTE Vol. 59 



able alignment of the projectors, and an 
analysis of keystone distortion, optimum 
lens focal length, and so forth. Projec- 
tors, however, are much better regarded 
as fixed mechanisms, which cannot be 
swiveled or otherwise adjusted from shot 
to shot. Furthermore, image distortion 
arising from projection is no more ob- 
jectionable in a 3-D than in a flat film, 
and can safely be relegated to the back- 
ground as a second-order problem,* pro- 
vided that no additional distortion is 
caused by beam-splitting or other 
methods. 

Hence it is only necessary to agree on 
the parallax at the screen between the 
left-eye image, regarded as a whole, and 
the right-eye image regarded as a whole. 
The alignment which we have adopted is 
that which differs least from the standard 
alignment of projectors for flat films, 
namely, one in which the image center- 
lines are superimposed. This can be 
succinctly expressed as Z CL = 0. Some 
consequences of altering the value of 
Z CL are discussed later in this paper. 

With t, the spectator's eye separation, 
substantially constant at 2.5 in., and with 
z CL assumed equal to zero, only two pro- 
jection factors need to be considered: 
F, the spectator's distance from the 
screen, and Af, the linear magnification 
which the image undergoes from film to 
screen. 

The Nearness Factor 

Referring again to Fig. 1, we can now 
advance to the first useful generalized 
concept, which appears not to have been 
remarked on before, though it is essential 
to any clear discussion of the production 
of 3-D films. It may be stated quite 
generally that, for any pair of optical image 
points, the ratio of the spectator's viewing dis- 
tance (V) from the screen to his distance (P) 

* Projector separation, t p , inevitably pro- 
duces some second-order distortion due to 
keystoning. This is analyzed fully in Ref- 
erence 4, together with some attendant 
anomalies of vision which help to rectify 
the shape of the image. 



from the fused image point is a constant, no 
matter whereabouts in the theater he may be 
sitting. 

This ratio we call the nearness factor 
(N) of the image point, and we may 
therefore write, 

- p -N (1) 

It is apparent that, 

if P = oo, N = (image at infinity), 

if p = v t N = 1 (image at the screen 
plane), 

if P = ;r> N = 2 (image halfway out 
to spectator), and 
so on. 

We can therefore state unambiguously 
for the first time where we wish a certain 
object in a studio set or on location to ap- 
pear in space to the spectator in the 
movie theater.* If the director says that 
he wishes an actor seated at a table to be 
represented at N = 0.5, while another's 
hand, outstretched toward the audience, 
is to be at N = 4, the stereotechnician 
knows at once that each spectator is to see 
the first actor at twice the viewing dis- 
tance to the screen, whereas the other's 
hand must come out from the screen 
three-quarters of the way toward him. 
The concept of the nearness factor is 
easily grasped, even by studio personnel 
to whom the rest of the stereo shooting 
procedure remains something of a mys- 



* In 1856, Sir David Brewster, writing 
about the wire mesh and wallpaper phe- 
nomena mentioned above, gave numerical 
data from which the constancy of N with 
change of viewing distance can be cor- 
rectly inferred. 6 But he failed to generalize 
the concept of the nearness factor, no doubt 
because of his preoccupation with the prob- 
lems of individual viewing. (It must be 
remembered that, prior to the invention of 
the incandescent lamp, only very rudimen- 
tary means were available for projection to 
large audiences.) Nonetheless, Brewster 
was far ahead of his time, and his book is 
even now worth reading. 



Spottiswoode. Spottiswoode and Smith: 3-D Photography 



253 



tery; but it affords the connection of 
ideas most necessary to establish between 
director and stereotechnician. 

Object Distances and Image Distances 

Next we must see how the position of 
the camera in front of the scene is related 
to the image of that scene in front of the 
spectator. Denoting by d n the distance 
from the camera to a given object point, 
there will be a corresponding image point 
seen by a spectator in the theater as hav- 
ing a nearness factor, N n . Specifically, 
we may refer to an image point at No 
(infinity) deriving from an object point 
at do, an image point at NI deriving from 
a point at d\, and so on. 

Now if we were to graph the distance 
of object points do, d\, d% . . . against the 
actual distance, P, of the corresponding 
image points from the spectator, it must 
not be supposed that the result would 
necessarily be a straight line. This 
represents an important but entirely spe- 
cial type of stereoscopic transmission; 
that is to say, one in which the rendering 
of distance is a linear function. We shall 
meet this again later on, but it is worth 
observing here that linear transmission 
does not of itself produce an orthostereo- 
scopic image, or one which is geometri- 
cally congruent with the original scene. 
There may be a multiplying factor either 
greater or less than unity by which a 
given length is stretched or shrunk, 
though of course uniformly throughout 
the scene. 

A New Unit: The Rho 

We now come to the problem of relat- 
ing do, di, d-i ... in the scene to -/V , NI, 
JV 2 ... in the theater. Here another im- 
portant step forward has been taken in 
the simplification of stereo calculations 
by introducing a new unit of distance. 
It can be shown that if a reciprocal dis- 
tance unit is employed, equal numbers of depth 
units in the scene will always correspond with 
equal changes of nearness factor in the cinema, 
no matter whether the transmission system is 
linear or nonlinear. 



Thus at one stroke a mass of difficult 
computation is done away with, and 
depth ranges in the scene can be manipu- 
lated by simple arithmetical addition and 
subtraction. 

The new distance unit has been named 
a rho ("reciprocal" denoted by the Greek 
letter p), and to bring it to a convenient 
size it is defined as the reciprocal of the 
distance in inches multiplied by an arbi- 
trary constant, the p constant (K), which 
has been set at 6,000. Thus we may 
write 



distance in p = 



6,000* 



distance in in. 



(2) 



This is equivalent to 500 divided by dis- 
tance in feet, and the units of course de- 
crease with increasing distance, and vice 
versa, as is shown in Table I. 



Table I 


Distance 


p 


Distance 


P 


100ft 


5 


6ft 




83 


50 


10 


5 




100 


33 


15 


4ft 


6 in. 


111 


25 


20 


4 


2 


120 


20 


25 


4 




125 


10 


50 


3 


4 


150 


7 


71 


3 




167 



Whereas distances in linear units are 
expressed as do, d\, d 2 . . ., the correspond- 
ing p distances are designated DO, D\, 
D% . . . . All measurements on the set 
and on location are made with a tape 
graduated in p on one side and in feet and 
inches on the other, for focusing. (In 
passing, it is worth noting that if lens- 
focus scales were engraved in p, they 
would be calibrated with equal sepa- 
rations for equal p differences, in place of 
the present unequally divided scales. 
Furthermore, depth of focus tables would 
need only one entry under each focal 



* Because of the superior convenience of a 
decimal system of linear units, we have re- 
cently converted to the metric system. 
1 metric p = 10,000 /distance in cm. 



254 



October 1952 Journal of the SMPTE Vol. 59 



length and aperture setting, instead of a 
multitude of entries relating to all pos- 
sible focus distances. But to gain these 
worth-while advantages, camera assist- 
ants would have to train their minds to 
udge distances nonlinearly, which would 
no doubt prove difficult !) 

In order to indicate how the general 
equation is derived, which connects the 



distance of objects in the scene with the 
distance of their corresponding images in 
the cinema from the spectator, it is neces- 
sary to return for a moment to the cinema 
and re-examine the parallaxes on the 
screen (z s ). Referring again to Fig. 1, 
and adopting the sign convention that 
uncrossed parallaxes are positive and 
crossed parallaxes negative, we can see 
at once that 



when z s = t, P = F/0, i.e., image at NQ (infinity) 

z s = 0, P = V/\, i.e., image at N\ (plane of screen) 

z s = t, P = F/2, i.e., image at N% (halfway out) 

z s = -2t, P = F/3, i.e., image at N 3 (f of way out) 

Zg = 3t,P = V/4, i.e., image at N^ (f of way out), and so on. 

Note: In our standard terminology, the letter t always represents the lateral distance 
between two optical axes, t itself denoting the separation of the human eyes (here assumed 
throughout as 2.5 in.), t e the separation of the camera optical axes, t p that of the projector 
optical axes, etc. 



In other words, equal negative incre- 
ments of parallax produce equal in- 
creases in N value. Moreover, these 
parallaxes are absolute; that is to say, 
they derive only from factors which are 
constant for any observer sitting in a 
given position in the cinema. They are 
irrespective of the size of the screen. 
But the corresponding parallaxes on the 
projected film, z p , are related to the 
screen parallaxes, z s , by an optical mag- 
nification, Af, which will be greater or 
smaller according as the screen is wider 
or less wide. Stated the other way 
round, a parallax of given magnitude on 
film will produce a greater or lesser 
stereoscopic depth according as the 
screen is larger or smaller. This impor- 
tant influence of screen size was first 
clearly stated, and its effects remarked 
on, by Professor Rule in the paper al- 
ready cited. 

Depth Content in the Theater 

At this stage it will help to introduce 
another concept, that of the depth content 
of the film in the cinema ; in other words, 
the range of depth in space which the 
image occupies. Let us assume a differ- 
ence in nearness factor of 2 between the 



front and rear planes of the image, which 
we shall express as *N%. Normally the 
range of N values would be from NQ 
(infinity) to A r 2, but from the point of 
view of the parallax analysis which fol- 
lows, the position of the N range in space 
is immaterial. For example, A -/V 2 might 
correspond to the range N\-N^ as in the 
recent McLaren cartoon film, Twirligig. 
Now it is apparent from what has been 
said that 



z s 
M 



(3) 



Since a change in N value of 1 results 
from a change of screen parallax of /, a 
depth content of ^N\ corresponds to a 
parallax on the projected film of 2.5/M 
in., a depth content of A jV 2 to 5/M in., 
and so on. 

Magnitude of Film Parallaxes 

In order to give a more concrete idea of 
the magnitude of the actual film paral- 
laxes when shooting for screens of normal 
commercial size, it may be helpful to de- 
viate for a moment from the main course 
of the argument. Table II has been 
prepared to show the total span of film 
parallaxes available (in mils) for films 



Spottiswoode, Spottiswoode and Smith: 3-D Photography 



255 




256 



October 1952 Journal of the SMPTE Vol. 59 



Table II 



Table III 



Magnifi- Screen 
cation Width 

(Af)* (WO 



Total projected film 
parallax, z p (mils) for 



M 



Minimum values of z p 
(mils) for SN = 0.1 



200 13ft9in. 12.5 25.0 37.5 

250 17 2 10.0 20.0 30.0 

300 20 8 8.3 16.7 25.0 

350 24 1 7.1 14.3 21.4 

400 27 6 6.25 12.5 18.75 

* Based on the standard 35-mm projector 
aperture width, 0.825 in. 

employing depth contents of A JVi, A jV 2 
and A A^ 3 . The *N\ column is of interest 
merely because there remain some con- 
servative spirits in the 3-D film field who 
think that no action should take place in 
front of the screen plane. 

In realizing a given depth content in 
the cinema, there is however another 
factor to consider. The representation 
of a given depth space may be imagined 
as built up of an infinite number of infi- 
nitely thin planes. Were this achiev- 
able, we might say that the stereoscopic 
resolving power was infinite, for the system 
would have an infinite capacity to dis- 
criminate depth. In actual practice, 
however, these planes will be replaced by 
more or less shallow zones, within each of 
which a position in depth will not be 
accurately reproducible. The depth of 
the zones will therefore be a measure of 
the stereoscopic resolving power of the 
system. These zonal depths may con- 
veniently be denoted by the change in 
nearness factor, bN, which they repre- 
sent, and we accordingly employ the con- 
cept of dN to clarify discussions of resolv- 
ing power, without suggesting that this 
will necessarily be the unit finally 
accepted.* 

Assume, then, that any volume of space 
denoted by A 7Vi is to be representable in 
10 zones of depth; in other words, dN 

* Experiments are being undertaken with 
trained observers to determine whether 
8N, dP or perhaps some other concept corre- 
sponds best with the subjective impression 
of depth resolution. 



200 


1.25 


(250 
<300 
(350 


1.00) 
0.83> 
0.71 J 


400 


0.63 



Note: The bracketed range comprises 
approximately 67% of existing motion 
picture theaters, as revealed in the recent 
SMPTE survey. 7 



= 0.1. We can then tabulate the mini- 
mum film parallaxes which it will be 
necessary to have recorded reproducibly 
on the projected film that is, after tak- 
ing into account all possible random par- 
allactic errors in previous stages of the 
transmission system. 

Table III shows that, for screens found 
in the majority of commercial theaters, 
the minimum reproducible film paral- 
laxes needed to achieve a depth resolving 
power of 0.1 do not much exceed the di- 
mensional tolerances of the film itself, let 
alone allowing for shrinkages which may 
occur at intermediate stages in commer- 
cial laboratory practice, or for mechani- 
cal errors in the stereoscopic adjustments 
of the camera. The need for extreme 
precision is still further emphasized by 
the fact that 8N = 0.1 is equivalent to 
only 20 separable zones in space for a 
normal 3-D film having a depth content 



The General Equation 

Reverting to our main theme, it will 
be evident that the greater the magni- 
fication, M, the greater the screen paral- 
lax to be derived from a given film paral- 
lax. Turning to the camera, it can be 
seen from Fig. 2 that an object point at a 
given distance produces a greater film 
parallax, (a) the longer is the focal 
length, f c , of the camera lens(es), and 
(b) the greater is the lateral separation, 
t c , of the lenses or optical systems. Thus 
an increase in these three factors, Af, f e 



Spottiswoode, Spottiswoode and Smith: 3-D Photography 



257 



and t c , increases the final parallax on the 
screen, whose absolute magnitude deter- 
mines the N value of the image point 
corresponding to the original object 
point, 0. In fact the product Mf c t c is 
combined into what is called the C factor 
in our general equation. 

This equation, which will be stated 
but not derived here, expresses the dis- 
tance, P, of a fused image point from the 
spectator in terms of the distance, p, from 
the camera of the original object point, 
together with the other variables of the 
transmission system. 



(4) 



Thus, besides M , f c , t c and p, which we 
have already mentioned, there is an A 
factor and a B factor. * The A factor, Vt, 
is a function of the spectator and his view- 
ing distance from the screen, as may be 
seen from Fig. 1 . The B factor denotes 
an important transmission concept, 
which is governed by the convergence of 
the camera optical axes (or its preferable 
equivalent, inward lateral displacement 
of the lenses relative to the films). 

The B factor can be related to a 
camera convergence half-angle, <p, and 
a projector convergence half-angle, 6, as 
follows, taking account of the fact that 
an optical printing displacement, z d , 
may have been introduced between the 
camera film and the projected film: 

B = t p - t 

+ 2M(f c tan <p - f p tan + z d } (5) 

If lens displacement is employed in- 
stead of toe-in in the camera, h, and pro- 
jector, H, we may write instead, 

B = t p - t + 2M(h - H + Zd) (5a) 

As a transmission factor, B may be 
very much more simply defined. Let 
m z t denote the screen parallax of a point 
which was at infinity in the scene, i.e. 
at DQ. Then 

B = >z. - t (6) 

Expressed in words, B is the excess of 
screen parallax of a point originally at 



infinity over the separation of the human 
eyes. 

B+, B = and B Transmission 

Three important cases now arise : that 
in which B is positive, that in which it is 
zero, and that in which it is negative. 
The discussion of the three types of 
stereoscopic transmission system will help 
to clear up the vexed question of camera 
convergence, a subject on which much 
ink has been spilt in the effort to estab- 
lish as fundamental relationships what 
have been only rough-and-ready rules. 
Several of these are now being purveyed 
by inventors in France, Germany and 
Holland, but on investigation they are 
found to be merely crude approxi- 
mations, the errors in which may be 
masked by the fact that they have been 
applied only to films projected on very 
small screens. 

Figure 3 shows in graphical form the 
principal characteristics of B-+-, B = 
and B transmission systems. It is to 
be noticed that both axes are scaled in a 
reciprocal type of unit, the x-axis in terms 
of D, and the ^-axis in terms of N. 
Hence the origin represents infinity on 
both axes. From Eq. (6) it will be seen 
that when B = 0, m z s = /. When, as 
here, the screen parallax of a point equals 
the eye separation, /, rays reaching the 
eyes will be parallel, as they are when re- 
flected from points at infinity. In other 
words, infinity in the scene (see definition 
of 2- g ) appears at infinity in the cinema. 
Thus a B = shot must be represented 
in Fig. 3 by a line passing through the 
origin, and no other type of shot can be 
so represented. Referring again to Eq. 
(6), if z s exceeds t, it must be that some 
point short of infinity in the scene pro- 
duces on the screen a parallax equal to / 
(because a point at infinity produces a 
parallax greater than t). Thus, when B 
is positive, a point nearer than infinity 
in the scene will correspond on the screen 
with a point which tends to appear at 
infinity. On the other hand, if "z, falls 
short of /, so that B is negative, it must 



258 



October 1952 Journal of the SMPTE Vol. 59 



N, 
Image 3/ 4 way out to spectator 4 

3.5 
Image 2/3 way out to spectator 3 
2.5 
Image 1/2 way out to spectator 2 
1.5 

Image at plane of screen 1 

/ 
/ 

/ 
0.5 
/ 
/ 

Image at , / Q 


B- B-0 B = B=0 B-f- 




/ 


/ 


/ 


/ 


/ 




/ 


p 




/ 


/ 


/ 


/ 


/ 




/ 


1 


/ 


/ 


f 

/ 


/ 




/ 




/ 


/ 


/ 


/ 






/ 




/ 


// 


/ 






/ 






/ J 

D = 0/ 
N>0/ 


// 


/ 

I 

I 






/ 






// 


/ 


1 

1 
1 
| 




/ 








/Xr>=o 

I^N=0 




1 

1 




/tan- 


c/t 






Region of negative f i 
D and N values /J 
1 ' ' 


(High C value) 
A 
(Medium C value 

, Ar 


/ D > (Distances in reciprocal units) 
1 N = 

J 

le) 


(Low C vah 



Fig. 3. The three types of stereoscopic transmission system: #+, 5 = and B . 



be that a point situated at infinity in the 
scene will appear at some nearer distance 
in the cinema. All examples of stereo- 
scopic transmission (in other words, all 



Class 

B = 
B+ 

B- 



instances of 3-D recording and repro- 
duction) must fall into one of these three 
classes, whose main characteristics may 
be exhibited thus: 

Name Characteristic 

Ortho-infinite Linear; infinity points correctly represented. 

Hyper-infinite Nonlinear ; objects short of infinity represented at 

infinity. 
Hypo-infinite Nonlinear; objects at infinity represented closer 

than infinity; cardboarding. 



In the example of a B system shown 
in Fig. 3, it will be noticed that infinity 
(i.e. D = 0) will appear on the screen 
plane, that is, at N\. This will occur, for 
example, if a shot of distant objects is 
taken with the camera axes parallel (<p = 
0), and projected with the projector axes 
toed-in so that the parallax of the aper- 



ture centerlines is zero (Z CL = 0). This 
frequently happens with amateur pro- 
jection of stereoscopic stills and 
movies. 

In short, the B factor can be varied at 
three stages in the production process, 
either angularly or by displacement, as 
follows : 



Spottiswoode, Spottiswoode and Smith: 3-D Photography 



259 



By By 

toe-in displacement 

In the camera <p h 

By optical printing z d 

By projection 6 H 

For ease of calculation, it is better to 
reduce all the stages to a displacement, 
using equivalences derived from Eqs. (5) 
and (5a). This also makes it possible to 
employ the simple graphical techniques 
of shot analysis described in Part II of 
this paper. Note that the effects of con- 
vergence and displacement (apart from 
second-order distortions in the case of 
convergence) are fully accounted for by 
the B factor alone. There is no problem 
of camera or projector axis alignment 
which cannot be very simply solved by 
the methods described here. 

Depth Range in the Scene 

Figure 3 illustrates another important 
idea, that of the depth range of a scene, 
which is defined as the range of dis- 
tances corresponding to a given depth 
content in the cinema. The symbol A is 
used to denote a difference of D values, 
so that, for example, AI signifies a range of 
reciprocal distances which will produce 
a depth content of A JVi in the cinema 
under given transmission conditions. 
AI may of course designate Z>i D Q or 
D 2 DI, and so on, as with its equiva- 
lent in the cinema, *Ni. It will be 
noticed from Fig. 3 that the depth range 
may be obtained from the depth content, 
or vice versa, by simple reflection through 
the appropriate characteristic curve, 
which will always be a straight line, no 
matter whether the transmission is linear 
or nonlinear. 

These curves are based on the funda- 
mental equation connecting reciprocal 
distances in the scene with nearness fac- 
tors in the cinema. It is derived from 
Eq. (4) and can conveniently be written, 



(7) 



Hence the characteristic curves of Fig. 
3 make an angle with the *-axis equal to 



tan 



sloping more steeply therefore as the C 
factor increases. We have already seen 
that an increase in the C factor increases 
the film and the screen parallax of a 
given object point in the scene. Hence it 
will also increase the depth content, 
A Af, in the cinema for a given span of 
depth range, A, in the scene. Or, to put 
this in a form more useful to the camera- 
man, the larger the C factor, the shal- 
lower will be the depth range in the scene 
for any given range of N values in the 
cinema. This is clearly shown in Fig. 3 
by the family of curves representing a 
5=0 shot. 

It can be shown algebraically that the 
depth range, A, is independent of the 
value and sign of the B factor, so that, 
for any transmission characteristic what- 
soever, we may write 

Djf - Do = (8) 



whence D 2 DQ = ^ 
C 



and 



(8a) 



(8b) 



where D is expressed in p and K is the p 
constant, 6,000. 

Finally, combining Eqs. (8a) and 
(8b), we may write 



Dl = 



(8c) 



This furnishes us with the necessary 
relationships between all the significant 
distances in the scene. It remains only 
to show how DI determines the conver- 
gence or effective convergence of the 
camera axes. 

If the camera axes are toed-in on a 
point at a certain distance, the film paral- 
lax, z c , of this point will be zero. If, 
then, the images are projected on a screen 
with Z CL = 0, the point will appear on 
the plane of the screen, i.e. at N\. 
Hence the original distance of the point 
was DI. In other words, when Z CL = 0, 



260 



October 1952 Journal of the SMPTE Vol. 59 







Fig. 4. Front side of the Stereomeasure (built in 1950), a calculator for 

relating D, A, M, f c> t c , cot <p and m d for all shooting conditions 

likely to be encountered in the studio and on location. 



the point on which the camera axes are 
converged is distant D\ from the camera. 
The half-angle of convergence being 
denoted by </?, it is evident that 



, 
tan- -, 



(9) 



where t c is in inches, and D\ in p. In 
terms of d\, the distance in inches from 
the camera to the point of convergence, 
we may write 

-i tc 



<f> = tan 



(9; 



If, which is preferable, each optical 
system is laterally displaced inward 
through a distance, h, in relation to the 
film, we may write instead, 



_ 



2K 



Or, expressed in terms of d\ t 

, fete 

h = o~7 
2d\ 



(10) 



(lOa) 



We suggest that h (and its projection 
counterpart, H} be denoted by the term 
edge-in to differentiate it from physi- 
cal convergence of camera and projector 
axes which is often conveniently de- 
scribed as toe-in. 

The Stereomeasure 

With the aid of the reciprocal distance 
system and Eq. (8) and its variants, an 
experienced stereotechnician can make 
all the necessary depth range and depth 
content calculations in his head, finally 
obtaining the values of <p or h from simple 
tables. However, as an aid to memory, 
these relationships and others have been 
embodied in a calculator, the Stereo- 
measure, which was designed and built in 
1950 and has since been used for every 
one of our productions. One side of 
this calculator is shown in Fig. 4. It 
gives immediate numerical answers to all 
problems of how the camera should be 
set up to produce the effect in space de- 



Spottiswoode, Spottiswoode and Smith: 3-D Photography 



261 



manded by the director, whether this be 
intended to soothe or startle, and whether 
the continuity from shot to shot be a 
matching or a deliberate mismatching of 
planes. Recently, with the aid of metric 
units and other simplifications, it has 
proved possible to design a much more 
compact version of the Stereomeasure 
which contains the same information but 
lends itself to quantity production. 

So far we have been concerned with 
the space relationships obtaining between 
a scene existing in real space and the 
same scene as reconstructed in stereo- 
scopic space by a binocular spectator sit- 
ting in the motion picture theater; and 
we have seen how these two quite differ- 
ent types of space can be related to one 
another by adopting new systems of 
measurement and comparison. 

Stereoscopic Magnification 

The next step is to examine how the 
size and shape of objects are affected by 
their stereoscopic transmission and repro- 
duction. It is well known that a monoc- 
ular image is essentially ambiguous, for 
the data it contains can (in the absence 
of other evidence) be construed by the 
spectator's mind as presenting a small 
object at a near distance or a much larger 
object farther away. By contrast, a bin- 
ocular image on the basis of the 
stereoscopic data it contains is entirely 
unambiguous; it is determinate in size, 
shape and position. But these char- 
acteristics do not necessarily conform 
with those of the object represented; 
its image in space may be larger or 
smaller, widened or elongated, nearer or 
farther away. These distortions are cer- 
tain to arise when presenting pictures on 
large screens; but whether they are ob- 
jectionable or not depends on a great 
many factors, some stereoscopic, some 
extra-stereoscopic, and some psychologi- 
cal, which will vary greatly from one 
spectator to another. Nonetheless, it is 
important to be able to determine mathe- 
matically what distortions the image has 
undergone, and this .must form an inte- 



gral partof the whole transmission theory, 
just as much as an analysis of waveform 
distortion forms part of the theory of elec- 
tronic amplification. 

Considering the stereo image of an 
object in the real world, we may call the 
ratio of the stereoscopic image size to the 
real object size the stereoscopic magnifica- 
tion, which may of course be greater 
or less than unity. It can be shown that 
the depth of objects may undergo one 
type of magnification (called depth mag- 
nification, m d ), while the height and 
width of objects dimensions between 
which a piano-stereoscopic transmission 
system does not discriminate undergo 
another type of magnification, called 
width magnification, m w . 

Stereoscopic magnification varies, 
among other things, with the size and 
sign of the B factor. In the general case, 
in which B 7^ 0, we may write, for any 
given plane in the image having a near- 
ness factor, N, 



Vt /B 



Mf c t\Nt 



+ 1 



(11) 



When .5 = 0, the expression in 
brackets equals unity, and the equation 
reduces to 



Vt 

Mf c t c 



It can also be shown that, in the same 
general case in which B ^ 0, the width 
magnification for an image plane having 
a nearness factor, N, is given by 



When 



0, this reduces to 



(12) 



(12a) 



Finally, since it is often the shape of 
objects which is more important to their 
acceptability than their absolute mag- 
nification along any dimension, it is 
helpful to introduce the concept of the 
shape ratio, /*. Then 



262 



October 1952 Journal of the SMPTE Vol. 59 



M = ^ = --( + l) (13) 



Since Eqs. (11)-(13) involve the B 
factor, it is convenient to have an expres- 
sion by which this factor can be easily 
reckoned when working out numerical 
examples. It is assumed that C and DI 
are known, as they will be when shooting 
conditions have been established. Then, 

B - 67M, - ' (14) 

where / c , t c and t are measured in inches, 
and DI in p. If d\ (in in.) is employed 
in place of D\, this expression becomes, 

B = - d -t (14a) 

The Orthostereoscopic Condition 

This is the condition of perfect image 
reproduction i.e. that in which the 
image as a whole is geometrically con- 
gruent with the scene it represents. So 
many inventors have claimed a system 
which produces a distortion-free image 
that it is worth investigating just what 
orthostereoscopy entails. For linear re- 
production it is necessary to have B = 0, 
and for geometrical congruence m d = 
m w = 1, so that /z = 1. Substituting 
m w = 1 in Eq. (12a), we have t c = t. 
Putting t c = t and m d = 1 in Eq. (lla), 
we have V = Mf c . Thus the three con- 
ditions for geometrical congruence are: 



B = 

t c = t 

V = Mf c 



(15) 



If the focal length of the camera lens 
and the screen size have been deter- 
mined, the spectator's viewing distance 
is fixed. Furthermore, for a normal 
space film having a depth content of A 2 , it 
can be shown that, under orthostereo- 
scopic conditions. 






12,000 



(16) 



when the rear of the scene is at Do. 



For example, if M = 300 (i.e. a 20 ft 
8 in. screen), and if/ c = 2 in., the near- 
est object to the camera must not be 
closer than 20p, i.e. 25 ft. Thus no 
shooting system can claim to eliminate 
distortion which does not comply with 
all the conditions of Eq. (15); and no 
system which complies with these con- 
ditions can claim to be practical for com- 
mercial films, since it would be limited 
to the taking of long shots. Hence it 
may safely be asserted (notwithstanding 
many statements to the contrary), that 
distortions are inseparable from stereo 
films as indeed they are from flat 
films and that it is therefore necessary 
to study their character and incidence. 

In Part II of this paper are to be found 
numerical examples which demonstrate 
very clearly the type of distortion to 
which a stereoscopic system is prone, 
especially when large B values are em- 
ployed. It is the depth of objects which 
tends to be most exaggerated, because of 
the squared term in Eq. (11); as the 
scene recedes, so it rapidly becomes more 
elongated. Experience confirms the ill 
effect caused by very large values of B, 
but it would appear that objects in the 
foreground and middle distance are the 
worst sufferers, perhaps because the eyes 
normally look downward on them more 
than on distant objects, so that one is 
more often reminded of their shape. 

Binocular Magnification 

There is however another kind of mag- 
nification to which the stereoscopic 
image is subject. Stereoscopic depth 
magnification is based on the supposition 
of a slight depth shift, dp, in the object 
position, which is then compared with the 
corresponding shift in the image position, 
dP. In other words, 

dP 



a concept which corresponds to that of a 
one-eyed spectator with a .foot-rule at 
the camera and in the theater al- 
though, of course, in the theater he would 



Spottiswoode, Spottiswoode and Smith: 3-D Photography 



263 



need two eyes in order to construct the 
depth image at all. Now if a two-eyed 
observer were stationed at the camera 
position, the front plane of a given object 
in the scene would subtend some angle, 
w, at his two eyes, and the back plane of 
the same objecc a smaller angle, a/. If 
co o}' were not too small an angle for 
the eyes to discriminate, the object would 
appear stereoscopically solid. Now sup- 
pose this object to be imaged and trans- 
mitted to a theater under given con- 
ditions. For a spectator of known posi- 
tion and characteristics, the same object 
will subtend at its front plane an angle 12, 
and at its rear plane an angle, 12'. The 
ratio of a small change in the image 
angle, 12, to a small change in the object 
angle, co, may be called the binocular mag- 
nification, m b , and an expression may be 
found for it which is analogous to those 
enunciated above in Eqs. (11) and (12). 



do) 



Vt 



(17) 



Note that m b is purely a form of depth 
magnification, having no relation to the 
width of the image, that it is independent 
of the value of B, and that (were the two 



kinds of magnification found to be multi- 
plicative in effect), when B = 0, m d = 
\/m b . Their inverse operation has im- 
portant practical consequences which 
will be discussed in Part II. 

The Complete Theory 

This short outline of fundamental prin- 
ciples can of course be developed very 
much further, and its fuller implications 
are set out in the work already cited.* 
These shed light on fascinating possi- 
bilities of set design which take advan- 
tage of the image distortions we have 
noted, just as the set designer of today 
makes fullest use of the potentialities of 
linear perspective. They help to ana- 
lyze many new techniques in cell and 
puppet animation. They enable the 
camera designer to lay down parameters 
for the construction of professional stereo 
film cameras. They enable a producer 
to undertake a complicated studio pic- 
ture in the confidence that all the prob- 
lems along the way titles, optical 
effects, back projection, stereo windows, 
and so on can be surmounted with a 
full knowledge of what is being done. 



PART II: PRACTICE 



It may be that a transmission theory 
such as this, containing as it must many 
new terms and concepts, will at first seem 
difficult to grasp, and perhaps too ab- 
stract for the practical needs of film 
makers. Yet just these objections were 
made when sensitometry was first intro- 
duced as a science. It was puzzling to 
have to think of densities and gammas 
and toe exposures when a mere twist of a 
lens diaphragm had previously seemed 
to suffice; yet today all these and many 
other terms are so much a matter of in- 
stinct that they trip off the technician's 
tongue with scarcely a second thought. 
The practice and nomenclature evolved 
here for the 3-D film have been carefully 
worked out with the needs of the pro- 
fessional film maker in mind. Very soon 



he is just as happy with depth ranges and 
nearness factors as he is with the rest of 
the science of film, because he can see 
what these things mean as soon as he 
starts to make his first stereoscopic movie. 

Within the limits of this part of the 
paper, we shall try to make the reader 
feel that he is sharing in the production 
of a section of The Black Swan, one of the 
many films now completed in accord- 
ance with this technique. We shall 
show how the stereoscopic constants are 
computed, how film parallax is after- 
wards determined, how camera errors, if 
present, may be corrected, and how the 
image in space finally appears to a mem- 
ber of the audience. 

The camera on which this film was to 
be shot consists of the twin assemblv de- 



264 



October 1952 Journal of the SMPTE Vol. 59 




Fig. 5. 3-D camera mounted on crane during filming of The Black Swan. 



picted in Figs. 5 and 6, this being the only 
equipment presently available in Eng- 
land for double-band 35mm shooting. 
As can be seen from the nearer view 
(Fig. 6), two Newman-Sinclair cameras 
are mounted on a stereoscopic base, 
shooting into mirrors set at 90 to one 
another, and having their apex facing 
the scene. 8 This arrangement provides 
for convergence by physically toeing the 
cameras inward, and it enables t c to be 
varied from a maximum of 8 in. to a 
minimum of 1.25 in. (2.5 in. with the 35- 
mm lenses). To set against this usefully 
wide variation, the camera has manifold 
disadvantages, chief of which are that a 
nonstandard image geometry results 
from reversal at the mirror surfaces, and 
that inaccuracies of setting due to faulty 
construction are so serious and unpre- 
dictable that a special optical printing 
technique has had to be devised to correct 
them. 



The first of the two shots we are going 
to consider in detail depicts the Male 
Variation danced by John Field. He 
finishes with a held pose which, in the 
stage version of the ballet, enables the 
audience to applaud. As a counterpart 
to this, the director, Len Reeve, proposed 
a stereoscopic curtain effect, making use 
of a pair of decorative banners which 
were to be raised before the scene at the 
end of the first shot, quite close to the 
audience's eyes. The immediate cut to 
the next shot would reveal a similar pair 
of banners at a slightly greater distance, 
hiding the scene ; and as these were raised 
out of sight, another pair behind them 
would be revealed, only to rise in favor 
of a third, and so on until Beryl Grey was 
discovered at the back of the set begin- 
ning her variation. 

Always when making a 3-D film the 
director will search for visual material 
which will enhance the sense of forward 



Spottiswoode, Spottiswoode and Smith: 3-D Photography 



265 




Fig. 6. Front view of 3-D camera showing Newman-Sinclair units in opposed 
positions and 90 mirrors. Matched lens pairs are available in the normal range 
from 35mm to 100mm, with coupled focusing; a centrally mounted Mitchell-type 
viewfinder is used for monitoring. 



and backward movement, of nearer and 
farther away. In unskilled hands this 
may easily degenerate into a trick, a 
mere device for showing off the third 
dimension to the best advantage. But 
the imaginative director will find that 
all kinds of new visual ideas will present 
themselves, which would be ineffective in 
the ordinary flat film, or which take on a 



new vitality in the more real world of 
3-D. The transition we are discussing 
proved very successful because the totally 
unexpected appearance of the banners 
caused the audience's attention to move 
rapidly into the extreme foreground, this 
being followed by the smooth withdrawal 
of attention to the back of the next scene, 
the time occupied being sufficient to 



266 



October 1952 Journal of the SMPTE Vol. 59 




Fig. 7. Slate 15 of The Black Swan. Camera out of picture on left, banners 
raised successively in pairs to reveal Beryl Grey in background. 



cover the musical transition and hide the 
break which was intended for stage 
applause. 

Computing the Stereo Settings 

The simple mechanics of this shot are 
shown in Fig. 7. But how is the stereo- 
technician on the set to ensure that the 
director's wishes as to the placing of the 
scene in space in the ultimate movie 
theater are precisely carried out? First 
it is necessary to decide the size of screen 
for which the film is to be shot, since this 



will determine Af, the one element in the 
C factor which is not controllable when 
shooting. If the anticipated variation of 
screen width is not very great, it is best 
to set M for the largest screen size, and 
accept some loss of depth on smaller 
screens. But if a wide range of screen 
sizes must be provided for, it is better to 
find a mean magnification so that the 
loss on the smallest screen is not too great, 
while accepting some divergence on in- 
finity points on the large screens unless 
these are corrected in an optical printing 



Spottiswoode, Spottiswoode and Smith: 3-D Photography 



267 



stage.* The Black Swan was to be pre- 
sented for 22 weeks on a screen only 10 
ft 4 in. in width (M = 150), and this sug- 
gested shooting it for a 1 5-ft screen (M = 
218), since it was known that results on 
even a 20-ft screen would then be entirely 
acceptable. 

Accordingly, the Stereo measure was 
permanently set at M = 218, this being 
analogous to the choice of a film emul- 
sion for a production, which gives rise to 
a fixed speed setting on the exposure 
meter. While the movement of the 
camera on its crane was being rehearsed, 
distance measurements were taken from 
it to the dancer and to different parts of 
the set. These measurements were made 
with the special Stereotape graduated in 
p on one side and linear units (for focus- 
ing) on the other. 

For the first shot, the entry in the 
stereotechnician's log begins as follows: 

Slate 35: LS Prince (John Field), who 
dances his Variation. Rear of set at 
10p. During the dance, camera tracks 
in, and the Prince finishes in MLS at 
33p. At end of dance, as Prince 
kneels, banners rise in front of him, 
covering whole frame, at 65p from 
camera. For continuity with follow- 
ing shot (already taken), banners 
should be at or around #2.75. 

It should first be determined whether 
this shot can be made with B = 0, i.e. 
with linear transmission, placing DQ at 
Op. Since the banners are to appear at 
-#2.75, the depth range is A 2 . 75 . The 
cameraman having selected a 35mm 
lens (f c = 1.38 in.), it can readily be de- 
termined by Eq. (8), or from the Stereo- 
measure, that t c = 2.1 in. However, 



* The excessive positive z s resulting from 
projection with too large a value of M. can 
be corrected by supplying a negative correc- 
tion of suitable size which will alter B and 
increase the N value of the nearest planes. 
This can be done by projecting with Z CL 
negative, but better by optical correction. 
Note that N factors will be increased both 
by the larger M and by the extra negative 
screen parallax. 



this value of t c is not obtainable on our 
camera with the 35mm lens, and the 
shot must therefore be recalculated for 
B-\-. The simplest procedure is as fol- 
lows. 

Taking the minimum setting of t c (i.e. 
2.5 in.), we then have M, f c and / c , and 
therefore the C factor. The most distant 
plane in the set, 10p (i.e. 50 ft), is set at 
infinity, DQ. The Stereomeasure, solv- 
ing Eq. (8) directly, gives 30p as the value 
of Z>i, and shows that the banners 
will in fact appear at A^.ya. 

Hence the stereotechnician's entry con- 
cludes, 

Treat shot as B+, with f c = 35mm, 
t c 2.5 in., and cot ^ = 160. D l to 
be at 30p. Nearness factor of raised 
banners works out at JV 2 . 75 , as desired. 

These measurements and calculator 
readings occupy only a couple of min- 
utes, and in a few moments more the 
camera is set to t c = 2.5 in. and cot p = 
160, the latter value having been ob- 
tained from scales on the Stereomeasure 
which relate t c and D\, as in Eq. (9). 

Two further points deserve comment. 
Firstly, what could have been done if the 
proposed settings had placed the banners 
in the wrong plane in theater space? 
Had they proved too far away, it would 
have been possible (a) to reduce the dis- 
tance in the studio between camera and 
banners, (b) to increase / c , or (c) to in- 
crease t e . Both (a) and (b) alter the 
composition of the shot, and so (c) is 
usually the preferable alternative. Had 
the banners proved to have too great a 
nearness factor, it would have been neces- 
sary to resort to the inverse procedure of 
(a) or (b), since the t c setting was already 
a minimum; This points to the need of 
incorporating the lowest practicable mini- 
mum t c in the design of the camera. 

Secondly, it may be asked what effect 
on the appearance of the shot is likely to 
result from changing B = to B-\-. 
Setting the rearmost plane at Do should 
of course place it at infinity, and clever 
set design will in fact produce a very 



268 



October 1952 Journal of the SMPTE Vol. 59 



marked elongation, an advantage when 
designing spectacular scenes. The back- 
grounds of normal interior sets are not 
likely, however, to suffer any appreciable 
deformation. It is the foregrounds, es- 
pecially when they contain objects of 
familiar shape, which may be more vis- 
ibly distorted. An example of a visible 
kind of stereo distortion is worked out 
from the data on the following shot. 
Practice, and frequent viewing of 3-D 
films, will tell the stereotechnician what 
is acceptable and what is not. It is un. 
likely, however, that he will satisfy every- 
one; for reasons that are not yet clear, 
people differ enormously in their sensi- 
tivity to stereoscopic shape and size. 

When the stereo settings have been 
made, one more step is required to be 
taken before the camera is ready to roll. 
This is the Stereo test, which provides the 
necessary data under the microscope to 
determine the actual, as contrasted with 
the nominal, values of cot <p (or h) and 
t c . To make this test, a small target 
board resembling a ping-pong bat is run 
out first to a distance of 40 p and then to 
22 p with the aid of the Stereotape, a few 
frames of film being exposed at each dis- 
tance. The lens focus is set at 15 ft for 
both shots, since the lens-to-film distance 
enters into the equations, and must there- 
fore remain constant. 

The shot which follows Slate 35 in the 
film had already been taken. It was the 
nearness of its front banner which had to 
be exceeded in 35, in order to produce 
the desired progression in space. The 
entry in the stereocontinuity book is as 
follows : 

Slate 15: Shot opens with pair of ban- 
ners in CS, filling screen, at 79p (6 ft 
4 in.). Banners raised out of picture 
to reveal further pair, and so on, till 
raising of 4th pair reveals Odile 
(Beryl Grey) in LS, who starts to 
dance her Variation. Camera static, 
rear of set at 13p (39 ft). At end of 
slate, Odile has danced into MS at 48p 
(10 ft 5 in.). 



Treat shot as 5 + , with/ c = 50 mm, 
t c = 1.25 in. and cot <f> = 220. Thus 
Do = 13p, D! = 44p, and D 2 = 75p, 
since AI = 31 p. Hence front banner 
is slightly closer than N 2 , actually 

#2.13. 

The method of working out this shot 
need not be repeated here, since it re- 
sembles the previous example and can be 
checked with the help of the equations 
already given. Although the stereotech- 
nician will seldom have to force the 
cameraman's hand in the choice of lenses, 
or the director's in the arrangement of a 
scene, he is nevertheless bound to be con- 
stantly preoccupied with the smallest 
value of t c which his equipment will pro- 
vide. In studio work, with its large 
depth ranges, he is likely to be pressing 
against this limit much of the time. In 
Slate 15, for example, 1.25 in. was the 
absolute minimum t c available with the 
50-mm lens, and had it been desired to 
hold the nearest banner farther away 
than NZ.I, while retaining it at the same 
field size, nothing could have been done 
except by allowing divergence to 
occur in the farthest planes of the shot. 

Image Distortion in the Theater 

The data already provided for Slate 1 5 
makes another interesting analysis pos- 
sible ; by studying the shape of different 
parts of the image, it is possible to get a 
clearer idea of the distortions set up in the 
motion picture theater. Let us consider 
the plane in the image corresponding to 
Beryl Grey's position when she has 
danced forward at the end of the shot, 
and is at 48 p. The spectator is assumed 
to be at a distance from the screen of 
2.5W. 

Example: It is required to find the 
depth magnification, width magnifica- 
tion and shape ratio for Slate 15 at a 
plane in the scene distant 48p from the 
camera, when the spectator is seated 
at 2. 5 W from the screen for which the 
film was shot. 



Spottiswoode, Spottiswoode and Smith: 3-D Photography 



269 



Object 


distance 














in rhos 


80 
















70 








:., 


Sign co 

+ V 
Vt 

Project 


nvention: 
parallax 
parallax 
on: ZCL = 


uncro 
cross 



ssed 
id 








60 S 


hot as on 
inal nega 
'actual) 
\ 




Banners 


2< 








on| 




// 


















50 


\ 


S/ > 


S 




















V 


',' / 






















SS 


/ 
















Shot 






< 
















as plannpd 


40 


/ / / 


\ 


















anted) 


s , 


y 


\ 








N -ve: 








\ ^' 


W/ 


Shot as obtained 






diverger 


ice 








s\f 


r 




'correcte 


d) 














s\ 


f/ 


20 
















S 




y 




10 














,' 


/* 














Z r ' in mils 


) 


+30 


+25 


+20 


+ 15 




-rlO 


+ 5 


-5 


-10| -15 


-20 


-25 



N factors at M . 218 i W = 15 ft) -^ NO NI N 2 N 3 

Fig. 8. Graphical analysis of Slate 35 of The Black Swan, showing relation between 

object distances in scene and nearness factors in cinema, together with 

method of postcorrection of convergence errors by optical printing. 



Object 
distance 
in rhos 


80 / XT,- 


~ Front 
banners 

(N2.85) 
















70 




/Front / t 

I 7 banners// 

' ?$ 


Sign convention: 
+ve parallax uncros 
-ve parallax crosse 
Projection: ZcL = 


sed 








60 


/ 
/ 
/ 


J/ 1 


A 

Shot as ( 
iginal neg 
actual 

)tained 
:orrection 
ted) 


>n 


i 




s: 


lOt 


/ 

50 ' 


'A 


Xj 

Sh 
r ( 

> 

/ 


\ 
ot as o 
>ptical 
i^correc 

Stereo 
est 














[wa 


Ued) 

\> 


40 /y> 


/ / aft* 

40p 
-2.2 mils 






N -ve 
Region 


of 








// 


// 

30 










ce 






/ 
/ / 
/// 
'/<*-* 


// 
/ 

22p 
+6.4 m 


) Stere< 
s f test 

10 


> 
















// 


^ 


'// 

+0.8 mils 
correctior 

+ 10 












+30 


+25 


^J 


// 

+ 15 




+5 




-10 




-15 


Z c i.in mil 
-20 


) 
-25 



N factors at M = 218 (W = 15 ft; * No NI 

Fig. 9. Graphical analysis of Slate 15 of The Block Swan, as Fig. 8, but showing 

also how the Stereotest readings are plotted to give the depth 

relationships on the camera negative. 



270 



October 1952 Journal of the SMPTE Vol.59 



Data: M = 218, /. W = 15 ft, and 

2.5 W = 450 in., .-. A = 1,125 sq in. 
Z>! = 44p, /. 48 P = AW 
j c = 50 mm = 1.97 in., t e = 

1.25 in., /. C = 536.9 sq in. 

From Eq. (14), 

536.9 X 44 



B 



6,000 
= 1.44 in. 



-2.5 



Hence, from Eqs. (11), (12) and (13), 

2.10 X 2.34 = 
2.00 X 1.53 = 
4.9/3.1 = 1.6 



m d 



4.9 
3.1 



From this it is safe to conclude, and 
can indeed be observed in the film, that 
some elongation of the side of the face 
and the shoulders will be noticeable, 
especially if the dancer turns so that the 
same features undergo differing magni- 
fication in quick succession. The more 
interesting case in which the dancer pir- 
ouettes with outstretched arms would 
call for integration, since the depth occu- 
pied by the arm stretching toward the 
camera would be nonlinearly magnified 
in a B-{- system. This difficulty can be 
overcome by employing an extension of 
the technique next to be described. 

Interpreting the Stereotest 

A graphical presentation, based on the 
principle of Fig. 3, greatly simplifies the 
study of scenes in space. So long as the 
distance of a plane in the scene from the 
camera is known, its position in space in 
the theater can be read off in an instant, 
together with the parallax which a point 
in this plane has produced on the camera 
negative, and finally the convergence and 
interaxial separation which obtained 
when the scene was shot. Figures 8 and 
9 are the representation of Slates 35 and 
1 5 respectively in The Black Swan. After 
development, synchronized left- and 
right-eye frames of the two Stereotests are 
cut from the negative tracks and placed 



under a special Swift traveling microscope 
with pilot-pin registration. By placing 
the two frames successively on the same 
pins, the parallax between corresponding 
points on the tests, at each distance, can 
be read off with great accuracy. These 
results from the actual film may be tabu- 
lated as in Table IV. 

Table IV 



z c (mils) 
40p 22p 


Slate 35 
Slate 15 


-4.3 

-2.2 


+7.2 
+6.4 



It should be emphasized that, because 
of the extremely small parallaxes needed 
to produce a 5 N of only 0.1 (see Table 
III), the most painstaking efforts must 
be made to keep microscope reading 
errors down to the lowest possible limits. 
Figures 8 and 9 show how the 40 and 22 
p points are plotted on a graph which 
represents z c on the *-axis and distances 
in p on the jv-axis. Since, on such a 
graph, B 0, B+ and B systems are 
equally represented by straight lines, it 
is only necessary to lay a ruler between 
the 40 p and the 22 p points. The result- 
ing line represents all the stereoscopic 
relationships in the negative, and the 
*-axis can of course be additionally grad- 
uated in N values for any assumed value 
of M by using the relationship, 

N=\-^ (-11) 

In Figs. 8 and 9 this has been done for 
M = 218, the magnification for which 
the film was shot. 

With the aid of a special protractor 
(not shown in the diagrams), it is possible 
to read off with great accuracy the actual 
values of t c and <p (or h) which obtained 
when shooting. These results may be 
tabulated as in Table V. 

No practical technique is imaginable 
for changing the magnitude of the C fac- 
tor after shooting (assuming that M re- 



Spottiswoode, Spottiswoode and Smith: 3-D Photography 



271 



Table V 



cot <f> t c (in in.) 

Wanted Actual Wanted Actual 



Slate 35 160 
Slate 15 220 



145 2.5 2.72 
234 1.25 1.42 



mains fixed), and therefore the slight 
error in t c will result in any given span of 
distances in the scene occupying a some- 
what greater span of nearness factors in 
the cinema than the stereotechnician 
intended. On the other hand, errors in 
the B factor resulting from inaccurate 
convergence can be perfectly corrected in 
an optical printing stage. This is be- 
cause convergence is essentially no more 
than the sideways displacement of the 
films relative to the images formed on 
them by the lenses, a fact which is easy to 
recognize in the case of h, but which 
applies also to <p. The method of cor- 
rection will be apparent from Figs. 8 and 
9. We know from the entries in the 
stereocontinuity log the p distances which 
were supposed to correspond with D 
and D 1 (i.e. .V and A^ in the theater); in 
Slate 35, D = 10p, and D l = 30p; in 
Slate 15, DQ = 13p and DI = 44 p. 
These pairs of points enable us to plot the 
"Wanted" curves for these shots. Figure 
8 shows that the N Q (Do) line cuts the 
"Wanted" curve at 10p, but the "Actual" 
curve at 15p, thus indicating that an in- 
creasing amount of divergence will be 
introduced at M = 218 for scene dis- 
tances greater than 15 p. Figure 8 also 
shows that by displacing the "Actual" 
curve sideways and in the increasing 
negative direction through 3.5 mils (as 
measured on the x-axis), N will be re- 
established at 10p, thus producing the 
"Corrected" curve. This is equivalent 
to giving the image a lateral displacement 
in relation to the perforations of 3.5 
mils, and this figure is accordingly en- 
tered in the correction table for the film. 
The reason why the "Corrected" curve 
still differs from the "Wanted" curve is, 
as explained above, that t c is slightly 



greater than it should be. This decreases 
the gradient of the curve, and thus am- 
plifies the change in N values for any given 
range of object distances. 

A correction of 3.5 mils corresponds to 
a change of nearness factor (8N) of 0.3 at 
M = 218. Corrections with this par- 
ticular camera tend, however, to run 
much higher, averaging about 10 mils 
and sometimes exceeding 25 mils (dN = 
2.2 at M = 218). This would mean 
that an object at infinity would be repre- 
sented stereoscopically as halfway from 
the screen to the spectator, or vice versa 
an error which would, of course, com- 
pletely destroy the 3-D effect of the scene. 
With screens of larger size than 1 5 ft, the 
error would be even greater. 

The result of the correction to Slate 35 
is that DQ is now correctly placed at N& 
when projected with M = 218. Had 
there been no error in t c , all other points 
in the scene would also have been cor- 
rectly placed. As it is, the banners at 
the end of the shot project in the theater 
at AYi instead of at A^.vs as planned. 

The analysis of Slate 1 5 (Fig. 9) is car- 
ried out in exactly the same way, and 
here the correction is found to be +0.8 
mils, the smallest ever encountered, the 
plane of D Q having been moved back 
merely from 13p to 11. 5 p. 

When better camera equipment is 
available, correction of every shot in this 
way will not of course be necessary. The 
technique of the stereotest will, however, 
continue to be useful as a laboratory 
check on the accuracy of the very precise 
camera adjustments required much 
as the routine ZMog E curve provides a 
daily or hourly check on film processing. 
But this by no means exhausts the possi- 
bilities of graphical analysis and optical 
stereo correction. For instance, when 
the layout of a set design is available, it 
becomes possible to study the mechanics 
of a complicated 3-D shot long before the 
film reaches the studio. Planes in space 
can be accurately charted, the necessary 
camera constants determined, and if the 
shot proves impossible, alterations can 



272 



October 1952 Journal of the SMPTE Vol. 59 



be made in the set before rather than 
after construction takes place. Again, 
when the public learns how to look at 
quick-cutting sequences in 3-D, it will 
often be possible to build these up out of 
material shot with an ordinary "flat" 
camera, giving each shot a single plane 

space by means of optical printing, and 
ring this plane if necessary by means 

optical zooms. The construction of 

:h a sequence is greatly simplified if it 
can be plotted in space, with the optical 
corrections read off from the graphs. 
The same technique may be applied dur- 
ing the editing stage of an ordinary 3-D 
film to readjust a shot which does not 
fit into the space continuity finally de- 
cided on. And lastly, optical printing 
may be used to match infinity points (or 
any other points) in converting films to 
use on very large or very small screens. 

Since optical printing is necessary with 
our camera to provide left- to-right image 
reversal, the transfer from original nega- 
tive to master positive is made use of also 
for the stereo correction and for the intro- 
duction of the necessary optical effects. 
Duping and printing then become nor- 
mal contact processes. There are of 
course limits to the width of the stereo 
correction which can be printed on a 
single film without trespassing too close to 
the final projector aperture. If the cor- 
rection is too large, it must be split be- 
tween the two bands of film. However, 
the larger the screen for which the film is 
shot, the smaller the absolute magnitude 
of the corrections. Furthermore, an ad- 
ditional width is provided for the cor- 
rections on each film by the printed-on 
stereo window. 

The Stereo Window 

This is the last printing stage to which 
the film must be submitted. The Black 
Swan has a fixed stereo window at ap- 
proximately N 2 (with M = 218), con- 
taining patented fusible components 
along its top and bottom edges, so that 
these contribute to the stereoscopic effect 
nearly as much as do the vertical sides. 



The window also could be incorporated 
at the master positive stage, but ex- 
tremely high contrast is necessary in a 
traveling matte to avoid fogging the 
image, and it is therefore best printed on 
at the release print stage. 

The stereo window is an essential com- 
ponent of most 3-D films, and its exist- 
ence and position in space must be con- 
templated from the beginning. More 
than half of the shots in The Black Swan 
were designed to occupy the full stereo- 
scopic space between NQ and N% (i.e. 
A #z) ; but as the scene was a ballet stage 
with dancers on it, effective space would 
have been seriously telescoped had not a 
forward window permitted a free move- 
ment of the image out to a distance half- 
way between the screen and the spec- 
tator. 

Appearance of the Scene in the Theater 

It is now time to stand back from the 
technicalities of production and ask how 
the two shots we have so often referred to 
appear to the ordinary audience in 
the movie theater. In the first place, 
whether they are conscious of it or not, 
spectators will see the entire scene framed 
behind the forward window, with the 
exception of one or two self-supporting 
objects such as the banners in Slate 35 
and Beryl Grey's arms and back-bent 
body in several shots. Since the screen, 
if free from blemishes, becomes invisible 
in a 3-D film, the window is easily mis- 
taken for it. Thus an audience might be 
led to comment on The Black Swan, 
"Practically nothing comes out in front 
of the screen," although, in point of fact, 
almost half the film does so. But the 
actual even if unrecognized use of 
theater space has one extremely impor- 
tant advantage which we have often 
heard commented on during commercial 
presentations of the films. Because of 
the increase of stereoscopic depth mag- 
nification (m d ) with distance from the 
screen, the spectator in the most distant 
balcony seat has a view of the film which 
is just as dramatically effective as that ob- 



Spottiswoode, Spottiswoode and Smith: 3-D Photography 



273 



tained by a person sitting comparatively 
close to the screen. 

In a stereocinema, distortions are 
usually least at a seating distance of 
2 to 2.5 W, and if but only if the pic- 
ture has been shot so as to be acceptable 
from this position, it will not as a rule 
appear unnaturally elongated even if 
viewed from much farther away. This 
is due to the inverse effects of m b and m w 
described under the heading "Binocular 
Magnification," earlier in this paper. 
Practical viewing experience reveals a 
substantial constancy in the depth- 
appearance of the image between the 
front and back seats of any normal thea- 
ter; but this will only be true if N values 
of 2 or more are employed continuously, 
for otherwise the distant spectator will be- 
come conscious of the gap existing be- 
tween himself and the screen. In our 
experience, provided that a sufficiently 
high level of technical perfection is 
achieved in the production and projec- 
tion of a 3-D film, nearness values as high 
as N s can be held continuously (for ex- 
ample, in a stereo window), with much 
larger values for the normal duration of 
an especially dramatic scene. 

Granted, then, that the scene in The 
Black Swfln will be framed in an N 2 win- 
dow; and that the audience, though for 
the most part unconscious of this fact, 
will be aware of seeing a picture totally 
different from the normal one, and differ- 
ent too from a stereo film presented 
wholly behind the plane of the screen. 
Granted this, what else will the audience 
be aware of? In the first place, the fact 
that their eyes can now scan the scene in 
depth means that the visual content of 
each shot will be much increased, and 
this in turn necessitates holding the shot 
longer on the screen. Today, when few 



audiences have seen 3-D films before,, 
quick cutting is ineffective, since each 
shot takes an appreciable time to estab- 
lish itself, after which its quick disappear- 
ance produces an effect of disappoint- 
ment and even annoyance. This is an 
extension of the principle on which color 
films tend to be cut somewhat slower 
than black-and-white ones. Secondly, 
the audience will be much more aware of 
the importance of depth relationships in 
a scene. Figure 10 shows a shot in The 
Black Swan which is of a type particularly 
impressive in 3-D. Whereas in a flat 
film it would achieve no more than the 
normal effects of deep focus, the third 
dimension gives the foreground figure an 
almost physical effect of size and mass- 
iveness. Even when the spectator is con- 
sciously watching the White Swan trying 
to make her presence noticed, he feels 
his eyes drawn to the menacing figure 
of the Enchanter standing much closer 
in the foreground and trying to banish 
her away. 

In the third place, the audience almost 
completely loses the impression that it is 
watching the photographic rendering of a 
scene. Actual reality seems to lie before 
it, and when the film is in color this 
reality is almost complete. 

Thus in the first scene we have been 
considering, the Male Variation danced 
by John Field will appear almost as if 
one were present in the theater. The 
raising of the banners right in front of 
the eyes produces by contrast a momen- 
tary feeling of complete surprise; and 
after a brief pause, the successive lifting 
of four pairs of banners out of scene 
flowing in the same unbroken rhythm 
disguises the fact that the scene has 
changed and thus introduces an element 
of fantasy when both a new decor and a 
different dancer are revealed. 



Part III: A Critique of Existing Procedures 



It may well be asked how, in the 
absence of a general transmission theory, 
proper camera and projection conditions 



could have been set up for the stereo- 
scopic films produced up to now and 
those in current production by other 



274 



October 1952 Journal of the SMPTE Vol. 59 




groups. The answer is threefold. First, 
the basis of an accurate theory was laid 
just prior to the war by Professor J. T. 
Rule, 8 and was apparently used by J. A. 
Norling in the production of his well- 
known and very successful films. Sec- 
ond, a number of pictures have been 
produced outside the United States on 
the basis of no proper transmission theory 



Fig. 10. The third dimension in this type of shot gives the foreground 
figure an almost physical effect of size and massiveness. 



at all, severe eyestrain having been 
avoided only because the size of the 
projection screen was very small. Third, 
and most recently, the early work of 
Rule has been overlooked or ignored, 
and a number of simplified procedures 
have been suggested, many of them the 
subject of exaggerated claims, such as 
that they completely eliminate dis- 
tortion, or that they make 3-D filming 



Spottiswoode, Spottiswoode and Smith: 3-D Photography 



275 



conform to the procedures of the flat 
film, yet without loss of effect. 

In this Part we shall discuss in some 
detail, using the method of analysis 
already derived from the general theory, 
two typical proposals, both in current 
use and both claimed to provide a 
perfect solution to all problems of 
stereoscopic transmission. The first 
makes use of a fixed interaxial separation 
of the camera lenses, and a variable con- 
vergence; in the second the convergence 
is fixed, but the interaxial separation is 
made variable. 

Viewing of Real Objects 
and Stereo Images 

It has been suggested notably by 
Dewhurst 9 in Great Britain and more 
recently by an influential group in the 
U.S. that the problem of 3-D filming 
is very simple: all that is necessary is 
to provide a fixed lens separation (t c ) 
approximating that of the human eyes 
and then converge the optical systems 
on some appropriate plane in the 
scene this plane appearing, of course, 
in the plane of the screen when the film 
is projected with Z CL = 0. It has been 
further suggested that the convergence 
control ought to be coupled to the lens- 
focusing mechanism in such a way that 
DI is always the distance to the plane of 
sharpest focus. Thus, following focus 
would automatically alter the con- 
vergence, and (since t c is already fixed) 
no special stereoscopic adjustments of 
any kind would require to be made. 
This, it is held, would reproduce the 
conditions of natural vision, and would 
provide strain-free viewing of the image 
by all spectators.* 

* The same idea has recently occurred to 
the first producer of 3-D motion pictures 
in Hungary, M. Felix Bodrossy. "The 
Hungarian method," he writes, "solves the 
problem simply and radically: it starts off 
from the way the eyes work, and imitates 
nature. The eyes always focus auto- 
matically and at the same time converge 
on the object they look at. Our cameras 
do the same thing." 10 



The parallel with the human eyes is 
simple and attractive; but, from what 
has been said above, it will be apparent 
that the viewing of a stereoscopic image 
cannot at present be made to resemble 
human vision at all closely. The image 
in space is not even an optical image; 
it is a mental construction from data 
supplied solely by overlapped images on a 
flat screen. This construction is accom- 
plished by methods not used in normal 
vision; for example, the spectator's eyes 
must remain focused at the screen dis- 
tance, but they will be varyingly con- 
verged according to the distance of the 
point of attention, which may be much 
nearer or much more remote. Further- 
more, in the real world, sense-data re- 
main more or less constant when spec- 
tator and scene are fixed; but stereo- 
scopic data may be made to vary widely 
according to projection conditions, and 
indeed cannot be kept constant when the 
size of the screen is changed. It is 
therefore not to be expected that a mere 
reproduction at the camera of the human 
eye separation in the absence of 
human viewing methods will of itself 
produce strain-free viewing. This can- 
not be so simply achieved until it becomes 
possible to create real or virtual 3-D 
images in space. 

Limitations of Fixed-f c Systems 

Meanwhile, stereo camera systems 
which make use of a fixed "human" lens 
separation of 2.5 in. must be treated as 
having an awkward limitation common 
to all fixed lens systems designed to film 
pictures for large screens. The trans- 
mission system obtaining with a fixed 
value of t c can be very clearly exhibited 
on a graph similar to Figs. 8 and 9. 
Reference to the section "Depth Range 
in the Scene," earlier in this paper, will 
show that the slope of the transmission 
lines is a function of the C factor (i.e. 
Mf c t c ) and t; and therefore, if M is as- 
sumed fixed for the film, t c is fixed on 
principle, and f c represents the focal 
length of the lens in use, all possible trans- 



276 



October 1952 Journal of the SMPTE Vol. 59 



Object distances 
from camera 
60 (in rhos) 



->XB+ REGION - 

_ -^ _ ^ _ - 



7717 
Region of / \S_ 
divergence I 



B- REGION 

\l \ 




N factors at M= 218 No 



Ni(Z CL =0) 



Fig. 11. Graphical analysis of "human vision" technique (i.e., t c fixed at 2.5 in.). 

For M = 21 8, f e = 50mm, all depth range possibilities are comprised in a series of parallel 
lines, such as those shown at 10p intervals, in the horizontally shaded region bounded by 
B = 0. For p values > 60 (distances < 8 ft 4 in.), extend the graph upward; forN> 3, 
extend it to the right. For/ c > 50mm, the parallel lines slope proportionately less steeply, 
and the depth range decreases ; for f e < 50mm, these lines slope more steeply, and the 
depth range increases. For M > 218, the region of divergence extends to the right, 
the intervals N , NI, N 2 . . . becoming proportionately smaller, NI remaining at z c = 0. 



mission lines on the graph will have the 
same slope, and must therefore run 
parallel to one another.* 

Figure 1 1 displays all the possibilities 
of such a transmission system, assuming 
t c = 2.5 in., and taking M = 218 and 
f e = 50 mm (i.e. 1.97 in.), so as to enable 
a direct comparison to be made with the 
shooting of Slate 15 of The Black Swan. 

Then, from Eq. (8b), 

* When the focus and convergence are 
coupled, this statement is not strictly true, 
for f e is properly the lens-to-film distance, 
which increases slightly as the lens is focused 
nearer. Hence, as DI is brought nearer to 
the camera, the C factor will increase 
slightly and the depth range will be corre- 
spondingly reduced. This is a second- 
order error, which is ignored in Fig. 11. 



D 1 - 



2.5 X 6,000 
218 X 1.97 X 2.5 



rhos 
13.97 rhos. 



This enables us to draw the B = line 
in Fig. 11, which also shows representa- 
tive transmission lines drawn in at arbi- 
trary intervals of lOp. The area under 
the B = Q line represents the B type of 
transmission, which gives rise to card- 
boarding and is therefore almost always 
undesirable; hence the camera conver- 
gence must never be set to give DI less 
than 13.97p (i.e. di more than 35 ft 9 in.). 
When the lenses are focused at infinity, 
they must not, as might be expected, be 
aligned with their axes parallel; alter- 
natively, if the lens and convergence 
mechanisms are coupled, the lenses must 



Spottiswoode, Spottiswoode and Smith: 3-D Photography 



277 




278 



October 1952 Journal of the SMPTE Vol. 59 



not be focused beyond 35 ft 9 in. for M = 
218. However, the minimum conver- 
gence will alter with the size of screen for 
which the picture is shot, and the focal 
length of the lenses in use, which might 
give rise to awkward mechanical com- 
plications. 

Much more serious than this, however, 
is the restriction on the depth range im- 
posed by such a method of shooting, and 
in the coupled arrangement the 
undesirable and highly artificial pushing 
of things nearer and farther away in 
space, which will tend to negative the 
3-D effect of the film, especially when 
complicated studio shots are undertaken. 
This can best be demonstrated by revert- 
ing to Slate 15 of The Black Swan, and 
showing how it would have appeared in 
space if shot by the "human vision" 
technique. 

Figure 12 is a repeat of Fig. 11, save 
that it is extended to cover a higher range 
of nearness factors, and is marked with 
the actual distances found in Slate 15. 
Curve 1 shows the result of setting the 
back of the scene (13p) at infinity, i.e. at 
DO, the method employed in the actual 
shooting. But now the front set of ban- 
ners (at 79p) will come out to -/V 4 7, i.e. 
(79 - 13)/13.97, which is almost J of 
the distance from the screen to any spec- 
tator. This is much closer t'lan the cut- 
ting continuity allows, and, in the 
opinion of many, enters the region of eye- 
strain. Certainly, the extreme nearness 
of the banners would be quite out of keep- 
ing with the rest of the film. No other 
fixed setting is possible, since it would 
produce divergence on the back of the 
set, even with the extremely modest as- 
sumed magnification of 218 (i.e. a 15-ft 
image in the theater). 

Thus a variable convergence for this 
shot is required by the "human vision" 
system under discussion, and we may 
conveniently assume that the converg- 
ence is coupled to the lens focus system 
in the way already described. The shot 
opens with the banners at 79p (6 ft 4 in.), 
and since at this distance, using a 50-mm 



lens at an aperture of //2.8, the depth of 
focus is only about 17 in., it would be 
necessary to focus with some precision for 
the distance of the banners themselves. 
This would cause them to appear in the 
theater at NI (see Curve 2), and once 
again the wanted effect would not be 
achieved, though this time the banners 
would be too far away, instead of too 
near. As the first pair was lifted, the 
plane of focus would move gradually far- 
ther away, passing through positions such 
as Curve 3. Following accepted tech- 
nique, the camera operator would follow 
focus in such a way that each pair of ban- 
ners in turn would occupy the plane of 
sharpest focus; but this would have a 
disastrous stereoscopic effect, in that it 
would bring all the banners into the same 
image plane (i.e. on the screen), and thus 
would wipe out the wanted recession in 
space. 

When the last banners had been raised, 
the focus would rest at 27p, and the back 
of the set would be correctly placed at 
13p. But towards the end of the shot, 
Beryl Grey dances forward to 48p from 
camera, where she would be out of focus. 
It is therefore necessary to alter focus 
again, and according to normal practice, 
the dancer would be held in the plane of 
sharpest focus, shown as Curve 4 in Fig. 
12. This would not only completely 
neutralize her forward movement in 
space, but would create divergence on 
the background, which would still be 
sufficiently in focus to be fusible. The 
only way out of the dilemma of neutraliz- 
ing depth is to juggle with the depth of 
focus, placing very near objects at the 
limit of the zone of acceptable sharpness 
in order to correct as well as possible 
their misplacement in space. This pro- 
cedure would unquestionably be much 
more inconvenient than having indepen- 
dently adjustable stereo settings for it 
would contradict accepted camera prac- 
tice and would give rise to a method of 
shooting in which the sharpness of focus 
was always under suspicion. 

The problem of divergence is even 



Spottiswoode, Spottiswoode and Smith: 3-D Photography 



279 



more intractable. Figure 12 shows that 
points at 13p will be separated by 6.26 in. 
on the screen instead of the proper 2.5 in., 
which would induce serious eyestrain, 
especially for spectators in the front rows 
of seats. If the magnification is raised 
from 218 to 300 (i.e. a screen width of 20 
ft 8 in.), the separation on background 
points would amount to 8.6 in., more 
than three times the separation of the 
human eyes. It should be remembered 
that divergence does not occur at all in 
natural vision; its physiological effect 
can be extremely uncomfortable. 

Distortions With Fixed-f c Systems 

But this is not the last of the disadvan- 
tages of a "human vision" camera ar- 
rangement. The use of large B factors 
entailed by employing a value of t c which 
is often too big for the size of screen and 
the depth range to be compassed, leads 
to serious distortion of the shape of ob- 
jects, as may be seen by a comparison of 
the example worked out under "Image 
Distortion in the Theater," earlier in this 
paper, with the same scene shot accord- 
ing to the precepts of "human vision." 
The data will be exactly the same, save 
that t c = 2.5 in. instead of 1.25 in., and 
that the dancer (who will be in the plane 
of sharpest focus) will be moved very 
slightly back from N\ .09 to N\. When 
these new values have been substituted, 
along with the unchanged data, in Eqs. 
(11) to (13), the results in Table VI are 
obtained, which for convenience are 
placed alongside the characteristics of 
the shot in the film. 

Table VI. The Black Swan, Slate 15, 

Stereo Distortions at the Plane of the 

Dancer's Final Position. M = 218; 

V = 2.5PF. 



By "human 
vision" 


In the 
film 


md 12.4 
niu) 3.4 


4.9 
3.1 


M 3.6 


1.6 



What has happened with "human 
vision" is that the width magnification 
has been kept down by making t c equal 
to t, which is one of the conditions for en- 
suring that m w 1 (see Eq. (15)). On 
the other hand, the depth magnification 
has increased enormously owing to the 
squared term in Eq. (11), and this has 
more than doubled the distortion of 
shape, as indicated by the figures for the 
shape ratio. 

This consequence of a "human vision" 
approach can be even more clearly dem- 
onstrated by the graphical technique 
already described. Figure 13 is in 
essence an enlargement of the relevant 
part of Fig. 12. It shows Beryl Grey's 
shoulder placed at 48p (10 ft 5 in.) from 
the camera, with arm outstretched as she 
pirouettes, so that the fingers are at 60p 
(8 ft 4 in.). The x-axis has been gradu- 
ated in N values, so that the value of P 
(distance from spectator to a point in the 
image) can be readily calculated from 
Eq. (1). By taking two points, one at 
the shoulder and one at the fingertips, 
the actual stereoscopic length of the arm 
can be found by simple subtraction, in 
spite of the fact that the magnification 
varies nonlinearly between the two 
points. Figure 13 shows that the arm 
length, as shot for The Black Swan, is 102 
in., whereas by "human vision" prin- 
ciples it would have been 208 in., or more 
than twice as great. The overall depth 
magnification works out as 4.1 in the first 
case, and 8.3 in the second, since the real 
arm length is 25 in.* As the dancer 
continues her pirouette, her outstretched 
arm moves into a plane parallel with that 
of the camera lenses, where its magnifica- 
tion will be uniform, and is given by m w 
in Table VI. The two shape ratios are 
therefore 1.2 for the film and 2.4 for 
"human vision," which is again twice as 
much distorted. 



* The overall magnification is of course 
lower than the magnification at the 
shoulder, because md decreases as N in- 
creases, and is therefore least at the finger- 
tips. 



280 



October 1952 Journal of the SMPTE Vol. 59 



Distance from 
camera, (rhos) 

60 



Plane of dancer's 
fingertips 



Curve (A) 



Curve (B) 



55 




50 





- - Plane of dancer's 
shoulder 



40 



N! 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 N 2 

Fig. 13. Enlarged section of Fig. 12, with "human vision" rendering of 
Slate 15 (Curve B) compared with shot in film (Curve A). N values may be 
converted to image distances from spectator (P) by Eq. (1) (P = V/N}. Assume 
spectator seated at 2.5W, i.e., 450 in. from 15 ft screen. Let P = image distance 
to dancer's shoulder, P' to her fingertips, when her arm is outstretched to the 
spectator. Hence, stereoscopic length of dancer's arm = P P'. 

From Curve B, "human vision," P = 450/1, P' = 450/1.86, .-. P - P' = 208 in. 
From Curve A, shot in film, P = 450/1.13, P' = 450/1.52, .-. P - P' = 102 in. 



The general applicability of a "human 
vision'.' technique can perhaps be most 
quickly judged by a statistical summary 
of the t e values employed in some recent 
pictures. The settings indicated by cal- 
culators such as the Stereomeasure and 
the Polaroid Interocular Calculator 
naturally give no preference to the value 
of 2.5 in., which is merely one setting in a 
wide and infinitely divisible range; but 
if, to give "human vision" all permissible 
latitude, we assign it the whole span of 
t c values between 2.3 in. and 2.7 in., we 
can analyze its limitations in the light of 
actual t c figures from productions. Pic- 
ture A is a studio film shot in sets of 
normal dimensions ; Picture B is a docu- 
mentary film shot principally out of 
doors. 



Table VII. Number of Shots Lying 
Inside and Outside the "Human Vision" 
Range for Two Typical Productions 



Less More 

than 2.3- than 
2. 3 in. 2.7 in. 2.7 in. 



Total 



Picture A 
Picture B 



16 
6 



20 
10 



1 
29 



37 
46 



Thus 46% of the shots in Picture A, 
and 76% of those in Picture B, fall out- 
side the "human vision" range when cal- 
culated according to the general theory, 
and without any preconception that t 
must always equal t c . It must be re- 
membered that the scene we have been 
discussing in such detail is not in any way 
abnormal, but is representative of in- 



Spottiswoode, Spottiswoode and Smith: 3-D Photography 



281 



numerable shots which try to exploit in- 
telligently the possibilities of a properly 
conceived 3-D system. Almost any 
method of stereoscopic shooting will 
handle mid-shots and long-shots (in 
which the depth range in reciprocal units 
is not great) quite satisfactorily, and will 
handle all shots provided that they are 
projected on small screens of 8-ft or 10-ft 
width. 

Limitations of Fixed-^ Systems 

The scheme for equating t c with t is by 
no means the only system put forward 
with the idea of simplifying and improv- 
ing 3-D film making. Another typical 
arrangement is that of "Verivision," 
which has gained some currency in 
Holland, the home of its inventor, Dr. 
F. H. Reijnders, 11 who hopes to secure 
completely distortion-free reproduction 
by fixing the camera convergence angle 
permanently at <p = 0.3.* At the same 
time t c is made variable, and set at such 
a figure that the fixedly converged lens 
axes always intersect in the nearest plane 
of the scene. 

It can readily be shown that "Veri- 
vision" (which disregards the effect of 
screen size) reduces to the simple rela- 
tionship DQ = 0.44Z>i. This is graphed 
for distance .increments of 10 p in Fig. 14, 
which clearly shows the possibilities and 
limitations of the system, f It has the 



* No explanation has been given for the 
choice of this particular angle, and Dr. 
Reijnders himself has prudently though 
perhaps optimistically claimed a patent 
on all values of <p between 0.15 and 0.6. 
f For purposes of comparison, the j-axis 
has been graduated with the values of t c in 
mm obtained from Dr. Reijnders' formula 
for different values of D\. 



advantage over "human vision" that, 
when the foreground plane is very close, 
t c becomes very small and the depth 
range is correspondingly increased, as 
may be seen by the increasing gradient 
of the curves corresponding to the larger 
p values. On the other hand, whereas 
some scenes can be reproduced by 
"human vision" with freedom from 
distortion (i.e., when Eq. (15) can be 
satisfied), "Verivision" cannot possibly 
eliminate distortion except under one 
special and unlikely condition. Ref- 
erence to Fig. 14 will show that all the 
characteristic curves intersect at a 
single point in the x-axis. To meet 
the first orthostereoscopic condition, 
B = 0, it is necessary that this point 
should correspond with N 0) and this, 
as the figure shows, occurs when z e = 
+20.5 mils, which from Eq. (3) gives 
M = 122, corresponding to a screen 
width of 8 ft 4 in., a size not particularly 
well adapted to commercial produc- 
tion. 

A further limitation of "Verivision" 
is that it imposes a method of filming 
which eliminates all N values greater 
than unity. 

To sum up, it is incorrect to suppose 
that the functions of convergence and 
interaxial separation are interch^nge- 
able, and that either can be fixed at an 
arbitrary value without impairing the 
flexibility of the system. The B factor 
and the C factor are entirely distinct. 
Moreover, since the C factor cannot be 
altered after shooting (given the size 
of the screen), errors in t e caused by 
incorrect filming methods cannot after- 
wards be amended. 



Shooting a 3-D film demands two 
major changes in production methods: 
a change of attitude on the part of the 
director, and a change of camera 
technique. 



Part IV: Conclusions 

The director of a 3-D film has an obli- 



gation to explore space relationships in 
his sets and between his characters which 
he would pass over in a normal flat film. 
If he neglects to do this, and merely em- 



282 



October 1952 Journal of the SMPTE Vol. 59 



t c (mm ) 
26.1 



D^rhos) 
60 



50 N values 
> 1 not 
permitted 



Region of 
divergence 

(M=218) 




15 No 10 
< Z c (in mils) * 

Fig. 14. Graphical analysis of "Verivision" technique (<p fixed at 
0.3, t c adjusted so that optical axes intersect at A)- Converging 
characteristics, shown at 10p intervals to 70p, show very limited depth 
range possibilities of the system, since only unshaded central area can be 
employed, and only that part of it bounded by available limiting values 
of t c . Note that B = only when point of intersection of characteristic 
curves occurs at N . This corresponds to z c 20.5 mils, or M = 122. 



phasizes the extra dimension by placing 
some meaningless post or tree or lamp- 
stand in the foreground of each shot, the 
audience will become as weary of these 
tricks as they became of the endless knives, 
ladders and hurtling baseballs of the pre- 
war anaglyphic pictures. 

The left- or right-eye track of a 35-mm 
double-band stereo film may without 
modification be presented to a wider 
audience in unconverted theaters as a 
normal flat film. However, the more 
successfully the film's director has 



thought himself into the new world of the 
3-D film, with its different space rela- 
tions, rhythms of cutting, and use of opti- 
cal effects, the less effective will be the 
flat version by comparison with what the 
same director would have made out of 
the same story had he concentrated on it 
alone. 

The translation of the director's ideas 
into 3-D film demands a comprehensive 
knowledge of stereoscopic transmission 
theory in just the same way as an 
electronic organ designer could not inter - 



Spottiswoode, Spottiswoode and Smith: 3-D Photography 



283 



pret a musician's wishes without a proper 
grounding in audio engineering. A 
stereo transmission theory has now been 
evolved, some elements of which we have 
described ; and to it has been added the 
beginnings of a new study of the psycho- 
logical aspects of stereo viewing corre- 
sponding in our analogy to a study of the 
modes of hearing. This theory is framed 
in a carefully studied terminology, which 
we hope may become the basis of an 
agreed nomenclature, for much time has 
often been wasted in new subjects by dis- 
cussing names instead of things. 

Once the transmission theory and the 
terminology have been established, cal- 
culators may be designed and stereo- 
technicians trained, so that the produc- 
tion of a 3-D film takes very little longer 
than a flat film. Spatial effects can be 
controlled with positive assurance, sets 
can be designed to achieve effects un- 
obtainable in the flat film, and back pro- 
jection and traveling matte processes can 
be developed with accurate knowledge of 
what is needed and of the tolerances 
which have to be met. 

These things cannot be fully achieved, 
however, if the design of the camera 
has been cramped by artificial restric- 
tions on the two main stereoscopic 
variables. Pictures which are shot for 
projection to small nontheatrical au- 
diences are indeed much less critical than 
pictures shot for the big screens in com- 
mercial theaters. The former may per- 
haps prove satisfactory if calculated 
by rule-of-thumb methods; for the 
latter much greater precision is needed 
if professional standards are to be met 
and audience discomfort and eyestrain 
avoided. 

Mathematical analysis is needed as 
a tool of space control in the filming of 
3-D pictures because the mental con- 
struction of a space image from data 
originally incorporated on two pieces 
of flat film bears only a remote re- 
semblance to the human process of 
seeing objects "in the round" as they 
exist in the external world. From this 



analysis, as we have seen, flow important 
consequences relating to the design of 
3-D film cameras. These may be 
summed up as follows. 

When M is large, and / c , in the 
interests of composition, is under the 
cameraman's control, t e must be ad- 
justable over a wide range, and in 
particular it must be capable of assum- 
ing very small values (of the order of 
1 in., or even less) to make possible 
interesting camera effects of extreme 
depth range both in the studio and out- 
doors. Large values of t e are essential 
for getting a big depth content on small 
screens, and for producing startling 
space effects on large ones. 

A fixed value of t c eliminates most of 
these possibilities, and greatly exagger- 
ates the distortion of objects to which a 
stereo system is in any case prone. If 
convergence and focus are coupled, other 
undesirable effects make their appear- 
ance : following focus helps to negate the 
movement of the camera through space 
by bringing everything in the foreground 
into the plane of the screen ; at the same 
time it becomes almost impossible to give 
near objects an N value much greater than 
unity, since they will automatically go out 
of focus in the attempt. But large N 
values quite apart from their occa- 
sional use as stunts are essential to the 
bringing of the picture close to every 
spectator, which is one of the outstanding 
advantages of the space film. 

A fixed value of <p has equally little 
logic to support it, and it takes the con- 
trol over the position of the image in 
space out of the hands of the cameraman 
and director to whom it belongs, and 
fixes it in accordance with some partial 
or erroneous theory. 

By contrast, the general theory out- 
lined in this paper unlike the patented 
procedures discussed in Part III does 
not prescribe any fixed camera technique 
or impose the use of any mechanical 
device. The director and cameraman 
should be able to make a free choice of 
the space effects they require the ulti- 



284 



October 1952 Journal of the SMPTE Vol. 59 



mate audience to experience; the stereo- 
technician will then be able to tell them 
how that effect can be produced, pro- 
vided that the camera equipment is 
sufficiently flexible and that psycho- 
logical viewing factors are properly 
taken into account. A true parallel, 
therefore, would be with the science of 
sensitometry, which does not attempt to 
prescribe fixed exposure settings, but 
does in fact analyze the consequences of 
making toe and shoulder exposures, 
altering the developing time, using 
different types of emulsion, and so on. 

In the same way, a valid transmission 
theory will enable the stereotechnician 
to determine what will be the geometrical 
form and position of the space image 
under all possible camera, optical 
printing, projection and viewing condi- 
tions. The effects of altering the space 
structure of the image in passing from 
shot to shot, as well as the space dis- 
tortion in individual shots, which are 
revealed by this analysis, will be evalu- 
ated in the light of previous experience 
in seeing 3-D films. Not only will the 
members of the production team them- 
selves become increasingly sensitive to 
the appearance of a new kind of film 
image, they will come to know what is 
and what is not effective in terms of 
audience response. 

Already a substantial body of pro- 
duction experience has been built up 
in the last two years in the course of 
developing and applying the principles 
outlined in this paper. A dozen films 
have been produced which have been 
commercially exhibited in half as many 
countries and seen by audiences now 
nearing the 3 million mark. 

If the full possibilities of the 3-D 
medium are to be exploited, the design 
of new cameras should be put in hand 
forthwith. Both theoretical analysis and 
experience point to the need of a wide 
flexibility in the t c and h variables, and 
of a precision of adjustment and film 
registration equal to that which must 
be attained in 3-strip color cameras. 



By using separate 35mm films for the 
left- and right-eye images, and by 
interposing the minimum number of 
additional glass surfaces between scene 
and film, these requirements can be 
achieved, though there is at present 
only one camera in the world (the work 
of J. A. Norling) of adequate precision 
and flexibility. 

Granted adequate cameras, there is 
no reason why films as ambitious as 
any now made in Hollywood should not 
be undertaken in the vastly more 
powerful 3-D medium. The knowl- 
edge thus acquired of production 
problems and audience response would 
remain of undiminished value were 
polarized projection to be replaced in 
the future by some type of integral or 
"free-vision" viewing screen; for though 
the means of separating the images may 
change, their appearance in space is 
likely to remain unaltered. For example, 
the parallax barriers recently classified 
by Kaplan in a paper of fundamental 
importance, 12 one and all give rise to an 
image geometry identical with that al- 
ready analyzed in Part I for a piano- 
stereoscopic system. 

As long as audiences will, therefore, 
accept for the time being the slight in- 
convenience of glasses which recent 
European experience seems to bear out 
there is no reason why major studios in 
the U.S. and Britain should further delay 
the production of at least a few dramatic 
films to determine whether or not they 
are the answer to a declining box office. 

At the same time, other developments 
in the projection field will be under 
way, which will still further close the 
gap between the spectator and the 
scene, and will reinforce that sense of 
participation in the drama of a film 
which alone, perhaps, can prevent the 
great audiences in the motion picture 
theaters from dissolving away into little 
audiences in front of home television 
screens. 



Spottiswoode, Spottiswoode and Smith: 3-D Photography 



285 



Acknowledgments 

For the material of Part II, the 
authors wish to express their gratitude 
to the staff of Anglo-Scottish Pictures, 
coproducers with Stereo Techniques, 
Ltd. of The Black Swan, and especially 
to Leonard Reeve, the director, Bernard 
Davies, who bore patiently with the 
camera, and Alvin Bailey, the editor. 
Our thanks are also due to Brian 
Anthony, head of the Optical Depart- 
ment, Denham Laboratories, who car- 
ried out the stereo corrections on The 
Black Swan and a number of other 
pictures. 

References 

1. J. A. Norling, "Three-dimensional 
motion pictures," Jour. SMPE, 33: 
612-634, Dec. 1939; "Progress in 
three-dimensional pictures," Jour. 
SMPE, 37: 516-524, Nov. 1941. Also 
"The stereoscopic art, Parts 1-4," 
PSA Jour., 17: 703-708, Nov. 1951; 
17: 738-742, Dec. 1951; 18: 19-25, 
Jan. 1952; and 18: 122-125, Feb. 
1952. 

2. Norman McLaren, "Stereographic ani- 
mation," Jour. SMPTE, 57: 513-520, 
Dec. 1951. 

3. Raymond Spottiswoode, "Progress in 
three-dimensional films at the Festival 



of Britain," Jour. SMPTE, 58: 291- 
303, Apr. 1952. 

4. Raymond Spottiswoode and Nigel 
Spottiswpode, The Theory of Stereo- 
scopic Transmission, University of Cali- 
fornia Press, Berkeley, Calif., 1953. 

5. John T. Rule, "The geometry of 
stereoscopic projection," J. Opt. Soc. 
Am. 31: 325-334, Apr. 1941. 

6. Sir David Brewster, F.R.S., The 
Stereoscope, John Murray, London, 
1856. Also see Edin. Trans., 15: 663, 
1846. 

7. Report on Screen Brightness Com- 
mittee Theater Survey, Jour. SMPTE, 
57: 238-246, Sept. 1951. 

8. L. Dudley, "Stereoscopy in the Tele- 
cinema and in the future," British 
Kinematography, 18: 172-181, June 
1951. 

9. H. Dewhurst, "Auto-precision stereos- 
copy," Phot. J., Sec. B, 92B: 2-24, 
Jan.-Feb. 1952. 

10. Felix Bodrossy, Magyar Technika, May 
1952. 

11. French Patent No. 938,023. M. Bon- 
net, "Etude du Procede de Relief 
'Verivision Holding,' " Bulletin de 
I* Association Fran^aise des Ingenieurs et 
Techniciens du Cinema, 9: 11-16, 1951. 

12. Sam H. Kaplan, "Theory of parallax 
barriers," Jour. SMPTE, 59: 11-21, 
July, 1952. 



286 



October 1952 Journal of the SMPTE Vol. 59 



Drawing in Three Dimensions for 
Animation and Stereoscopic Processes 



By ERNEST F. RISER 



Stereoscopic mathematics are far too complicated to apply easily and speedily 
to every point in the many drawings and cells required to obtain motion in 
animated films, or in a usable volume of art for commercial or lecture pur- 
poses. The following procedure was developed to allow stereo drawings to 
be made with a minimum of time and effort and still produce practical three- 
dimensional material. 



AN THIS METHOD the artist draws to scale 
directly from the subject as in conven- 
tional art practices but also adds the 
scale distance he may be from the object, 
as well as the depth of subject measure- 
ments, to obtain stereoscopic effects. 
He is able to compute the amount of 
stereo depth necessary in any part of the 
drawing; and he is able to determine the 
size of the image which will appear on 
the screen. Stereo rules and principles 
as outlined in this paper do not neces- 
sarily apply to true stereoscopic me- 
chanics, as these practices were developed 
only while making this simplified pro- 
cedure workable. Single objects for ad- 
vertising and lecture purposes drawn in 
stereo differ from scenic stereo art in that 
they are usually small in size and show 
considerable detail without much height, 
width or depth. This necessitates spe- 

A contribution submitted June 25, 1952, 
by Ernest F. Hiser, Dept. of Medical Illus- 
tration, School of Medicine and University 
Hospitals, The University of Oklahoma, 
Oklahoma City 4, Okla. 



cial consideration when preparing them 
for three-dimensional viewing. 

Figure 1 (a) shows the left (L) and right 
(R) eyes from above, looking to infinity 
with parallel lines of sight. While it is 
optically possible to widen these twin 
lines to some extent, natural visual ad- 
justments do not depend on this ability. 
Stereoscopic vision is practically non- 
existent beyond 1000 to 1500 ft, but from 
200 ft to within a few inches of an ob- 
server the portrayal of a third dimension 
becomes a very noticeable accomplish- 
ment. The parallel sight lines indicated 
are the width of the eyes, a maximum of 
2f in., and for all practical drawing pur- 
poses that figure is used. 

Any object within the range of stereo 
vision will cause the eyes to converge or 
"toe in" just enough to focus on that 
object and its particular point of interest. 
While this point of interest is actually a 
point, a vertical flat plane at that point is 
important in this method of making 
stereoscopic drawings. This flat plane 
is to be considered as the "window- 
plane," and is located exactly where the 



October 1952 Journal of the SMPTE Vol. 59 



287 




viewing screen will be upon projection, 
or where the aerial image appears upon 
viewing by other methods. The point 
of focus or interest for any object can be 
at any depth level within the boundaries 
of that object. The term "window- 
plane" derives from the fact that in a 
stereo picture all objects appear to stand 
out or recede from the black edge of the 
picture as if they were being viewed 
through a picture frame, or window. 

Although the point of focus may be 
placed on any part of the subject for 
emphasis, a dead-center location will give 
the maximum overall stereoscopic effect 
for the subject. When the picture area 
includes several objects, a dead-center 
point of focus will provide excellent 
depth separation. All objects drawn to 
the front of the window-plane will appear 
nearer to the observer, while all objects 



drawn to the rear will appear farther 
away. This plane interposed into a 
stereo scene with the eyes set at infinity 
will cause the sight lines from L and R 
to pass through it as L 1 and R 1 (2f in. 
apart), and the two flat drawings which 
constitute one stereo drawing will have 
their identical components separated by 
that scale distance on the window-plane. 

In Fig. 1 (b), the lines of sight are toed in 
until the point of vision is focused upon 
the window-plane. All points on one 
drawing which are to appear on this 
plane will coincide exactly with the same 
points on the other drawing. 

In Fig. l(c), the point of focus is brought 
forward to A, where the toe-in or crossing 
of the eyes causes the lines of sight to pro- 
ject upon the window-plane as R 1 and 
L 1 , and in reverse order to that of in- 
finity. As there is a limit to the toe-in 
effect (with the danger of obtaining ghost 
images), this amount should again be not 
more than 2f scale in. on the window- 
plane. The point where the sight lines 
cross, A, will always be exactly one-half 
the distance of the window-plane to the 
observer. Since the coincidal points of 
focus are separated by toe-in as in (b), the 
object focused upon will appear nearer to 
the observer. 

In order that these measurements be 
made practical, it is essential that the 
screen size is visualized. A 40-in., 6-ft or 
18-ft screen with a well placed and 
planned image size must be kept in mind 
throughout the process so that parallax 
on the window-plane can be computed 
easily for its comparative to scale likeness 
on both drawings. 

The first drawing to be made can be 
designed without too much regard for 
stereo principles. It should have correct 
perspective, and the heavier lines should 
be drawn to the front of the subject as in 
accepted art practices, with the lighter 
lines to the rear giving an illusion of 
depth or roundness to the drawing. 
This illusion of depth in the first draw- 
ing can be intensified to advantage in this 
type of work. A good stereo drawing is 



288 



October 1952 Journal of the SMPTE Vol.59 



4 FT. STEREO 
SCREEN OP PLANE 




Figure 2 



finished when a satisfactory delineation 
of the subject is obtained in the rather 
stiff and hard-outlined techniques pecu- 
liar to animation. In this process the 
first drawing is always called "L," or 
"the left-eye drawing" for convenience 
and to avoid confusion when many draw- 
ings are at hand. 

Figure 2 is an extreme example with an 
extra-large subject, and shows the ap- 
proach to the second stereo drawing 
while illustrating the first step in sketch- 
ing a 2-ft transparent cube as it would 
appear in stereo from a distance of 3 ft 
to the artist; the focal point selection is 
dead center. The picture is to be shown 
on a 4-ft screen. The L and R eyes are 
placed at scale distance in scale inches 
apart below a cross section of the subject. 
(FP is the floor plan of I, the completed 
left-eye drawing) . Vertical lines of sight 
to infinity show where points of vision 
cross the window-plane, or screen. MN 
and MF are the "maximum near," and 
the "maximum far" limits which can be 



drawn with the point focus in the center 
as indicated without causing eyestrain or 
ghost images. These limits increase as 
the distance from the artist to the subject 
is increased, and it is obvious that as 
these limits increase so does the depth of 
the entire picture. Infinity backgrounds 
may be added to assist further in depth 
perception. MN is exactly halfway 
between the window-plane and the ob- 
server, while MF is the same distance on 
the other side of the plane. Lines 
marked * are the outside limits of the 
picture as a whole, and run from the eyes 
to W the edges of the picture or win- 
dow-plane. MN and MF will always 
place L and R 2f in. apart on the 
window-plane. 

Lines drawn from L and R through the 
subject area and crossed at the point of 
focus (1), will indicate the amount of 
shift (2), or line displacement, necessary 
for both near and far stereoscopic effects 
within the cross section. 



Ernest F. Hiser: Animation and Stereo Processes 



289 



POINT 
SHIFT 




Figure 4 



PUNCH SHIFT FOR 

SINGLE PLANE BACKGROUND 



USE OPPOSITE 
SHIFT FOR CELL 
FOREGROUNDS 




For further simplified operation, Fig. 3 
shows that the amount of shift can be 
estimated quickly by a simple crossing of 
the L sight line at the point of focus by 
the R sight line. All points to the front 



of the focal point, as well as those at the 
rear are to be offset in exact proportion 
to the width of the shift-cross or scale, 
and in the direction of the corresponding 
arrows A and B. It is obvious that this 
shift will be greater or narrower in width 
as the distance L and R is nearer or far- 
ther away from the window-plane or fo- 
cal point. Lines (a) and (b) are a re- 
minder of the maximum separation that 
can be made for near and far objects. 

Figure 4 illustrates a simple object with 
exaggerated drafting for easy visualiza- 
tion of the mechanics of the shift-scale, 
and brings the problem to completion for 
both L and R drawings. A is the orig- 
inal, or L, drawing. B is the cross sec- 
tion of the object with exaggerated shift- 
scale in place and with all major points 
projected over to the right where the 
cross section is duplicated. Point shifts 
are measured in accordance with the pro- 
portional widths of the shift-scale, and a 



290 



October 1952 Journal of the SMPTE Vol. 59 





Figure 6 



new, or right-eye cross section is super- 
imposed over the L cross section. Lines 
are projected down from all points to 
complete the R stereo drawing. 

Additional cross sections should be 
made of any part of the subject which 
changes contour, and from which point 
shifts can be measured from the shift- 
scale. It is possible when drawing con- 
sistently on the same distance scale (as in 
animation) to estimate the R shifts on 
either side of the point of focus by the eye 
alone with considerable accuracy, as 
soon as the near and far shifts of the scale 
are known for the object being drawn. 
Exaggerations for special emphatic effects 
in both near and far points of interest can 
be obtained by increasing or decreasing 
the shift-scale measurements to unbal- 
anced amounts. The shift-scale should 
be drawn in perspective as in the subject 
when the scene is large enough to include 
noticeable perspective. 

When a flat-plane background is to be 
located at any point between the back 
limits of the subject and infinity, only one 
drawing is necessary. In this case the 
paired L and R drawings are made on 
cells for use over the single-drawing back- 
ground. This background will need a 
stereo-shift in proportion to the desired 
depth in the scene which is accomplished 



on a standard animation board, as in 
Fig. 5. The background paper is 
punched twice to proper offset measure- 
ments for the L and R image shift and is 
used underneath the corresponding cell 
to complete either the L or R assembly. 

Subject parts may be labeled at their 
different stereo levels, and flat-plane fore- 
grounds and details may be added in this 
manner to complete a scene without 
working on the main L and R drawings. 
The labels or details are drawn on cells 
which are double shift-punched for the 
correct plane, and are placed on top of 
the background and L or R assembly for 
photographing. 

Figure 6 is a scientific stereo drawing 
made with a back mount for the subject 
simulating a background, a device which 
sometimes assists the observer in obtain- 
ing good stereo vision. Figure 7 is a 
drawing without a supporting back- 
ground, and in this case the stereoscopic 
effect depends entirely upon the shift 
drawn in the R-eye drawing. Actually, 
the R drawing is the only one where 
depth measurement and shift are neces- 
sary. Entire animation sequences can 
be drawn first as for regular animated 
films, can be checked for timing and 
accuracy, and be otherwise completely 
finished before the R-eye series is begun. 



Ernest F. Hiser: Animation and Stereo Processes 



291 





Figure 7 



In cases where old two-dimensional films 
can be shown to advantage stereoscopi- 
cally, the original drawings can be used 
as the entire L series. 

The process of photographing the com- 
pleted stereoscopic drawing assemblies 
depends upon the equipment available 
and the aims of the project. As there 



are several good procedures, the one cur- 
rently in use will provide the method 
necessary to turn the completed work into 
practical commercial, teaching or lecture 
material. 

Reference 

1. Norman McLaren, "Stereographic ani- 
mation," Jour. SMPTE, 57: 513-520, 
Dec. 1951. 



292 



October 1952 Journal of the SMPTE Vol. 59 



nimation for 
Individual Television Stations 



By ERNEST F. RISER 



With the advent of television and the consequent increased use of the animated 
film for advertising, it has become necessary to devise quick and inexpensive 
methods for the small studio to produce such films. In this paper some 
simplified techniques for animation are described. 



JL HERE is no need to discuss or evaluate 
the use of animated films as an advertis- 
ing or spot-announcement medium. 
The problem is, how can such work be 
produced by the average small studio 
art department at a time and price 
ratio that will allow for speed, re- 
vamping, and the visual appeal necessary 
for local and short-contract sponsors? 
Farming out films to commercial firms 
with their expensive production methods 
may be desirable but is out of the 
question unless the sponsor or depart- 
ment contemplating the work is fortunate 
enough to have funds warranting such 
productions. Simpler and cheaper 
methods of animation must be devised 
if this medium is to be utilized to full 
advantage. 

No claim is made for extensive 
originality in presenting these animation 
techniques. This paper was primarily 

A contribution submitted on June 25, 
1952, by Ernest F. Riser, Dept. of Medical 
Illustration, School of Medicine and 
University Hospitals, The University of 
Oklahoma, Oklahoma City 4, Okla. 



designed to present routines capable of 
producing usable film material as 
speedily as possible. Comparatively 
simple or simulated animation can be 
prepared after one has made a study of 
"stop-motion" the basis of all anima- 
tion. Throughout this paper, the term 
"animation" will be used to indicate all 
phases of stop-motion. 

The staff artist does not need to be a 
photographer to do animation, as the 
photographic part of the process is 
mostly a fixed thing, and all camera 
operations necessary for the methods 
used are easily applied. Figure 1-(1) 
shows a simple camera stand with an 
interchangeable animation board which 
will work equally well under the camera 
and over the illuminated tracing table. 
Using the same board for two purposes 
will also eliminate error in register and 
layout. 

It is well to remember that the effect 
of animation is the aim, rather than true 
animation, and that the effect processes 
cannot encompass some types of fluid 
motion. To obtain smooth motion in 
human and animal figures, or similar 



October 1952 Journal of the SMPTE Vol. 59 



293 




Fig. 1-(1). A, animation stand complete; B, animation board on pegs under camera 
(the same peg holes fit on tracing table at right which is illuminated by circular 
lamp); C, camera; D, lamp under animation stand for transillumination; and , 
transformer for laps, fade-ins and fade-outs. 

Fig. l-(2). Method of drawing on paper with cell overlay. 



complicated multiplaned objects, draw- 
ings such as those made by commercial 
animators will have to be approximated. 
Although it is possible to simplify these 
units to a great degree, too much 
simplification will produce an effect so 
amateurish that an entire sequence may 
be spoiled. 

The "story" of the action, whether 
it be for a chart, graph or complicated 
pictorial delineation must first be broken 
down into scenes or action units as one 
would imagine them on the screen: 
titles, sound, action, etc., in proper 
order. Along one side of this script 
little sketches are made at each change 
of scene or action tempo. These assist 
in visualizing the film, and form a basis 
for determining the overall mechanics 
of timing and the animation methods to 



employ. This layout is called the 
"storyboard" (Fig. 2). 

The artist "times" the action by 
imagining that action as taking place, 
even going so far as to draw rough graph 
lines and details as he would have them 
appear for each little sketch on the 
storyboard. With the help of a stop 
watch he marks the times obtained in 
seconds on each sketch, as well as after 
each legend, rest and title. The sound- 
track wordage is also timed and balanced 
against the animation timing at this 
stage of the production. The artist will 
now be able to add "holds," or places 
where the action stands still, to his 
script while commentary wordage con- 
tinues. It is seldom necessary to have 
continuous action throughout a se- 
quence, in fact, holds are desirable for 



294 



October 1952 Journal of the SMPTE Vol. 59 



12- Storyboard- RADIOLOGICAL SAFETY. 
Scene Commentary-Action 



Scl5- 




Scl5 

6 Are 

ce//s 




015 -'THE BOMB EXPLOSION AS AT HIROSHIMA FORMS 
A BALL OF FIRE APPROXIMATELY ONE THIRD 
OF A MILE IN DIAMETER, WITH A TEMPERATURE 
OF 100 MILLION DEGREES FAHRENHEIT, AND IS .. 
SIMILAR TO A SMALL PIECE OF THE SUN 1 H/\ 

A15 - Drg. showing 'peaceful city' skyline 

ClJa-'A TERRIFIC SHOCK WAVE WITH WIND VELOCITIES 
OF 500 to 1,000 MILES PER HODR, AND THE 
EMISSION OF GREAT QUANTITIES OF RADIATIONS 
MORE INTENSE THAN X-RAYS FOLLOWS THE BLAST' 

A15a- Blast animated with 'radiations', etc /fid 

C15b-' OFFICIAL FIGURES SHOW THAT AT HIROSHIMA 
THE BLAST KILLED AND DISABLED 260 OF ITS 
300 REGISTERED PHYSICIANS; 1,800 OF ITS 
2,400 NURSES AND FIRST-AID WORKERS; 
DESTROYED 26 OF THE 33 FIRE STATIONS , 
AND ALL OF THE HOSPITALS. A LARGE NUMBER 
OF PERSONS DIED LATER FROM INTERNAL BURNS 
CAUSED BY THE RADIUM-LIKE EMISSIONS FROM 
THE BLAST. THESE RADIOACTIVE FISSION 
PRODUCTS OF U235 LIBERATE ALPHA, BETA, 
AND OAMMA RAYS, AS WELL AS NEUTRONS' 



L22 - INJURIES EXPECTED 

(Legends fi-fo giving injury figures) 



EXTERNAL BODY RADIATION IS SIMILAR TO THE 
EXPOSURE FROM A GIANT X-RAY MACHINE , EXCEPT 
THAT THE RAYS COME FROM ALL DIRECTIONS. 
THE MAXIMUM PERMISSABLE EXPOSURE IS BASED 
UPON 'TOTAL BODY RADIATION' . EXPOSURES OF 
10-25r MAY PRODUCE SMALL INJURIES, 25-100r 

SOME INJURIES, 100-30Or WILL RESULT 
^ J ttfll30Qr JENSA FATAL 



Fig. 2. The storyboard, with working data and times computed. 



visual observation of scenes showing a 
sponsor's product, etc. 

The amount of film necessary for the 
production can then be estimated from 
the total number of seconds or frames 
obtained. As sound film is projected 
at the rate of 24 frame/sec, the number 
of drawings required and the measure- 
ment of line displacements necessary 
for smooth motion can also be calculated 
from these timing figures. Some action 
speeds or drawing advances will require 
a two-frame exposure for each drawing, 
while others will use more or less ex- 
posures for smoothness of action. Cau- 
tion must be used in the preparation of 
the exposure figures: it is very easy 
accidentally to clip off a few words of 
commentary, or to allow action to 



proceed too fast or to drag along 
upon the television screen. 

Drawings for television should be 
made on paper which has a decided 
tone, so that unpleasant smears will not 
occur on the screen. On all work of 
this kind, pure white of any type should 
be used sparingly if at all. The art 
work should be somewhat stiff and hard, 
with considerable emphasis on contrast. 
Soft, delicate drawings may be used for 
background work in some instances, 
although detail cannot be followed 
easily by the viewers when this type of 
art is in motion. 

Every phase of motion in the story 
need not be animated. When the 
action is very obvious, such as in the 
opening of a package, gadget manipula- 



Ernest F. Riser: Animation for Television 



295 



tion, or the placing of many objects in 
the scene, numerous drawings can be 
avoided by fading-in the change with 
laps or dissolves. A little arrow or 
other indicator pointing to the ap- 
proaching fade-in phase area will focus 
attention on the spot so that the desired 
eftect will not be missed. It is possible, 
with much hard work and many draw- 
ings, to produce such fancy and intricate 
animation at a critical point that the 
subject matter is lost to the observer. 

Examples of simple animation can be 
demonstrated by a conventional display 
ad or catalog layout, i.e. a drawing with 
several legends and indicator lines upon 
it as follows: 

a. The drawing is to appear first without 
catch lines. These appear singly with a 
little arrow pointing to the corresponding 
area. Each legend and its arrow vanishes 
for a second or two before the next legend 
appears. . . . This effect is obtained by 
the use of little lettered cards for the 
legends and a single cutout arrow which 
are placed in position on the drawing 
before each exposure. Rests of one or 
two seconds are exposed between the 
legends. A piece of clear plate glass is 
placed over the assembly during exposure 
to make the items lie flat and smooth. 
Single-frame camera work is not necessary 
unless the number of frames exposed must 
be exact. 

b. The drawing is again to appear first 
without legends. This time the legends 
appear singly as before but remain in the 
scene once they appear. Corresponding 
indicator lines run from each legend 
directly to the point in question. In this 
case the lettering and lines are done on a 
celluloid overlay, or "cell." This cell is 
put in register over the drawing so that 
the assembly appears complete, as at the 
end of the sequence. The drawing is 
placed upside down under the camera, 
and the scene is photographed backwards, 
that is, by scratching off the lettering and 
lines from the cell one at a time with a 
blunt point while reading the timing 
figures on the storyboard in reverse order. 
The artist ends with only the drawing 
remaining under the blank cell. After 
this section of film has been processed it 



is reversed (turned end for end) for pro- fe 
jection, and the effect will be as desired. 

c. Dotted or solid lines encircling any p 
particular area on the drawing for em- I 
phasis may be made to appear by this cell- I 
and-reversal method either by "flashing- I 
in" the line as a whole, or by causing the I 
line to "draw itself in," which is accom- I 
plished by scratching out only a small I 
portion of the line at a time while using I 
evenly timed single-frame camera ex- 
posures. Again, the timing or exposure 
sheet is read in reverse for correct filming 
and effect. 

Basic graph or chart forms and photo- 
graphs may be used instead of drawings 
for the master background, and lines, 
lettering, figures, etc., may be made to 
appear as desired by this method. Two 
cells can be used over a background at 
the same time when separate action 
lines cross each other or when the 
subject matter is more complicated. 
Scratchboard can also be used for the 
background when additional scratch- 
off work is necessary. The animator 
can visualize many variations of this 
process to apply to any story situation 
if he will take the trouble to lay out and 
time a sample storyboard for a sequence 
which is to appear as above. 

Layouts using black backgrounds are 
sometimes permissible for various types 
of work, especially when light or colored 
lines and lettering constitute the bulk 
of the copy. A good black is not always 
easy to get from a photographed card; 
and painted-out, scratched-out or 
covered-up lines are apt to show up 
as such. One way to avoid this trouble 
is to make the original layout in black 
on white paper. A litho negative is made 
of this drawing in the proper size for 
animation. Lines, detail and copy are 
drawn with transparent color as desired 
on this negative. It is placed in upside- 
down position under the camera as 
before, with a lamp underneath the 
transparency ready for transillumina- 
tion. All top lamps are switched off. 
The lines are then painted out in reverse 



296 



October 1952 Journal of the SMPTE Vol. 59 



storyboard order with a matte black 
watercolor. This process gives a true 
black background with brilliantly colored 
detail, and will show no evidence of 
construction upon construction. Such 
work when photographed on color film 
will produce the necessary grays for 
black-and-white television projection and 
will also provide a film for future color 
television. 

It is a good idea when working in 
color for black-and-white projection to 
photograph a frame or two of each color 
in the brand of paint used and make a 
gray scale from these tests. As few 
colors photograph exactly as they appear 
on a card or on celluloid, this test will 
also serve as a guide for art work de- 
signed to be shown in color. 

The above method is also invaluable 
for fast, easy production of line diagrams 
or pictorial "growths" when a black 
background can be used. It is also 
valuable for title work and designs 
which "draw themselves." In title 
work using color, the black background 
can be changed to any color desired by 
winding color film already exposed for 
the title back in the camera to the be- 
ginning of the title and double-exposing 
a piece of colored paper over the shot 
already made. A good paper to use 
for many effects in animation is artist's 
pastel velour, which will not reflect 
highlights because of its matte surface. 
During photographing, the transillumi- 
nation lamp is, of course, turned off 
and the top ones turned on. This 
method is limited only by the animator's 
imagination, and will produce many 
color effects from any black-and-white 
original. 

Cutout overlays may be utilized in 
many ways to supplant a drawing, 
photograph or chart, and to add interest 
or detail to any type of scene. These 
cutouts must be made accurately to 
register exactly with the drawing under- 
neath. Cutouts should be made on 
opaque paper and have their edges 
blackened before use. To register cor- 



rectly, cutouts are cemented to acetate 
cells with rubber cement, which will 
not cause wrinkles or waves in the cell. 
When registered on a regular animation 
board with its registering pins, assembly 
will be easy and successive phases will 
match line for line. Legends and 
indicator lines may be inked in on the 
same cell as the cutout. 

The first form of animation as in- 
vented by Winsor McKay consisted of 
a series of drawings with subject and 
backgrounds complete, and with action 
similar to the little "flip" books for 
children. This type of animation was 
very difficult and time-consuming, as 
tracings of all lines had to be extremely 
accurate in all parts of the drawings. 
In this type of work the lines and detail 
which stood still for some time were 
subject to a definite "shimmy." A 
variation of this process is still used 
when every part of a drawing is under- 
going a continuous change. 

Fluid-motion animation is best 
handled in pen-and-ink outline with 
considerable contrast in shading or 
coloring. Any part of the drawing 
which does not move, even for a short 
time, should be made on a cell to 
eliminate work and stabilize the action. 
When no background is needed, the 
action is drawn on toned or colored 
sheets of paper plus the required number 
of work-saving cells. When the back- 
ground is an inherent part of the scene, 
or continuous fluid motion is required 
over a combination layout, all action is 
drawn on cells. The lines and outlines 
are inked in on the front of the cell, and 
opaque color is painted within the 
outlines from the back, which preserves 
the sharpness of the inked lines and 
provides opacity to the cell. Action 
may be drawn on paper and transferred 
to cells as in the cutout method if 
desired, since the results will be the 
same (Fig. l-(2)). 

In animating any action the "ex- 
tremes" the first and last drawings of 
the scene or action phase are sketched 



Ernest F. Hiser: Animation for Television 



297 



first. A study of the action will then 
show which parts of that action will 
require emphasis or near-stops between 
the extremes. With these drawings 
made, the animator then has the first 
and last drawings as well as the major 
in-betweens of the contemplated action, 
and the assembly will appear as a series 
of drawings showing the major phases 
of a subject such as might be prepared 
for publication in an advertisement or 
article. 

The storyboard will then show how 
much time is to be consumed between 
these majors. Dividing the times ob- 
tained into frames will give the proper 
line displacements or advance necessary 
on each drawing for correct and smooth 
action, as well as the final number of 
drawings required to fit the action. It 
is well to keep in mind the fact that the 
more drawings there are to be made for 
a certain action (involving the least line 
displacement) the smoother that action 
will be. If the number of drawings 
actually required is considerably de- 
creased, line-displacement distances on 
consecutive drawings must be increased 
and a greater number of frames exposed 
for each drawing. These increases 
Can easily result in a very jumpy se- 
quence. 

Slow or gradual changes are generally 
preferable in advertising and lecture 
films, and, at sound speed, a J-in. line 
advance with a two-frame exposure on 
a drawing which has a working field of 
approximately 8 X 10 in., is about the 
greatest advance which can be made 
between drawings without obtaining 
an irritating jumpiness. Even this does 
not appear too smooth at times when 
great contrast is encountered in art 
work. A J-in. advance with a single- 
frame exposure will have much smoother 
motion, although the tempo might be a 
little fast. It is always better to make 
a few extra drawings than to have the 
action pass by too quickly or shimmy 
badly because of excessive exposures. 



After the majors and in-betweens are 
prepared the drawings are checked for 
all lines and components which will 
stand still for any length of time during 
the action. These lines are drawn on 
cells for stabilization and elimination 
of shimmy. Although regular com- 
mercial animators use a complicated 
three-cell arrangement it is seldom 
necessary to go beyond one cell for 
simplified advertising and spot films. 
When even one cell is used over a 
background or for work-saving reasons, 
it will be necessary to expose all drawings 
of that series through the same number 
of blank cells before and after the cells 
are used because of the extra tone 
imparted to a scene by any cell overlay. 
After the cells are made, the extremes, 
majors and in-betweens on paper are 
inked in (minus the lines on the cells). 
In finishing the in-betweens it is not 
necessary in fairly rapid action to obtain 
the same degree of exactness in drafts- 
manship as on the majors, although the 
line displacements must be accurate. 

Each drawing is then marked as to 
consecutive number in the scene, number 
of exposures required, the number of 
the cell which must accompany it, and 
any other data considered important 
to the animator. 

To eliminate excessive background 
area, or to localize action or interest, 
a foreground can be made of colored 
velour paper with a round or otherwise 
suitable opening in it for the action to 
show through. This foreground is 
placed over the drawing assembly on 
the registering pins before exposure of 
the scene. 

The above basic production methods 
are as near to actual commercial anima- 
tion as the television animator needs to 
go for the production of ordinary local 
film needs, and by using one or all of 
the above even in one sequence when 
they will blend together much valu- 
able material can be designed. The 
effect or presentation of the subject is 
all that matters; the manner of obtain- 



298 



October 1952 Journal of the SMPTE Vol. 59 



ing that effect is secondary as long as 
the methods employed do not result in 
a visual hodgepodge of artistic media 
without advertising or story value. 
Once more, the entire effort depends 
upon the design of the storyboard 
the blueprint of the production. If 
the storyboard has been carefully drafted 
with full regard to the story, and timed 
with a view to good presentation, an 
overall technique will become apparent 
which includes one or more of the above 
processes of simplified animation. The 
method using the least amount of art 
work should be selected whenever 



possible, as in many cases the simpler 
technique will present the subject more 
graphically than will the complicated 
one. 

Animation should only be used when 
the subject cannot be presented by 
regular photography, or when a new 
method of approach, unusual effects, 
or the presence of artistic values can 
play an important part in the instructive 
aspects of the advertisement or story. 
Animation should also be used as an 
adjunct rather than as the principle 
illustrative medium unless the entire 
subject benefits by graphic animated 
pictorialization. 



Ernest F. Hiser: Animation for Television 



299 



X-ray Motion Picture Techniques Employed 
in Medical Diagnosis and Research 

By S. A. WEINBERG, J. S. WATSON, Jr., and G. H. RAMSEY 



With Appendix by W. E. SGHADE 



X-ray motion picture techniques are reviewed with attention to relative 
exposure requirements and ability to record detail. Direct cineradiography 
on full-scale screen-films provides the best reproduction of detail but does not 
at present reach true motion picture speeds. Cinefluorography is the most 
flexible and least expensive of the traditional methods. Because of harmful 
effects of radiation cinefluorographic examinations of human subjects must 
generally be limited to a relatively few seconds. The length of examinations 
can be much prolonged with the help of screen image intensification. Un- 
fortunately the x-ray motion pictures made by kinescope recording are not 
yet satisfactory from the point of view of detail. 



-1- HERE ARE a number of ways of 
making x-ray motion pictures, each one 
of which has its special virtues and limi- 
tations : 

1. Successive frames of film are 
exposed directly to the x-rays which 
have passed through the subject. 

2. Instead of being exposed directly 



Presented on May 2, 1951, at the Society's 
Convention at New York, by S. A. Wein- 
berg, J. S. Watson, Jr., and G. H. Ramsey, 
Dept. of Radiology, University of Roch- 
ester School of Medicine and Dentistry, 
260 Grittenden Blvd., Rochester 20, N.Y. 
This investigation was supported in part 
by a research grant from the National 
Heart Institute of the National Institutes 
of Health, Public Health Service. The 
anpendix was contributed in June 1952 
by W. E. Schade, Hawk-Eye Works, East- 
man Kodak Co., Rochester, N.Y. 



to x-rays, each frame of double-coated 
film is compressed at the moment of 
exposure between a pair of fluorescent 
intensifying screens. Excited by x-rays, 
the screens emit violet and blue light, 
thus exposing the film. 

3. A fluorescent screen is set up per- 
pendicular to the x-ray beam as in 
fluoroscopy. The image formed on the 
near side of the screen is copied by a 
motion picture camera to a much re- 
duced scale. 

4. The screen image is picked up by 
a television camera, and a kinescope 
recording is made of the action. This 
method is still in the experimental stage. 

Direct Cineradiography Without 
Intensifying Screens 

Methods 1 and 2 are generally re- 
ferred to as direct or full-scale cineradi- 



300 



October 1952 Journal of the SMPTE Vol. 59 



ography. In both cases the shadow 
image on the film is a little larger than 
the subject; and in this respect the 
methods are alike. There is, however, 
a striking difference between them in the 
matter of photographic speed. Mainly 
because of the poor absorption of hard 
x-rays by the film emulsion, an exami- 
nation recorded on single-coated film 
without screens, at diagnostic kilovoltage 
levels, may require 25 or 50 times as 
much x-ray intensity as a similar exami- 
nation recorded with the aid of intensify- 
ing screens. Method 1 is, in fact, so 
"slow" that its use is confined to small, 
easily penetrable subjects of thin cross 
section. The subject, a worm or insect, 1 
the thorax or abdomen of a mouse, 2 
is positioned in front of the aperture 
of a 35mm camera, and the x-ray beam 
is directed through the subject to the 
film. During the pulldown phase of the 
camera the film must be protected from 
x-ray fogging, either by reinforcing the 
shutter with lead or by interrupting the 
primary circuit of the x-ray generator. 3 
It so happens that the ability of the un- 
aided film emulsion to resolve fine detail 
is relatively very good. This is for- 
tunate, because the significant detail 
of small subjects approaches the micro- 
scopic. 

Direct Cineradiography With 
Intensifying Screens 

With the aid of intensifying screens 
direct cineradiography becomes a much 
"faster" technique and can be applied 
to much larger and denser subjects. The 
size of the film frame may be anywhere 
from 5 by 5 in. to 12 by 15 in., the latter 
size being large enough to include an 
adult chest. When properly exposed, 
the so-called screen-films are recognized 
models of radiographic quality and 
would appear at first glance to be an 
ideal, if rather expensive, medium for 
making x-ray motion pictures of human 
subjects. Unfortunately it is not easy 
to impart rapid intermittent motion to 
large strips of film. Machines have been 



designed with the hope of making 12 or 
1 6 pictures/sec, but few, if any, of them 
can be counted on to function at more 
than 4 or 5 pictures/sec without frequent 
breakdowns. 4 The necessity for sand- 
wiching each frame of film closely be- 
tween fragile screens at the instant of 
exposure makes the problem doubly 
difficult. Both film and screens pick 
up multiple scratches, dust and frag- 
ments collect at the aperture, and, worst 
of all, poor contact between screens and 
film results in grossly unsharp pictures. 

The most successful attempts at full- 
scale cineradiography at true motion 
picture speeds have been made on con- 
tinuously moving 15-in roll film exposed 
to extremely brief pulses of radiation. 
The single-coated film passes over an 
idle roller surfaced with a low-lag 
phosphor, the film being thus exposed 
in contact with what amounts to a single 
intensifying screen. With an experi- 
mental condenser discharge apparatus, 
as many as 100 exposures/sec have 
been made in this way. 

As a rule, however, the motion studies 
made by method 2 are not true x-ray 
motion pictures, but simply rapid serial 
x-rays exposed at from 1 to 5 pictures/ 
sec. Rapid serial x-rays have been 
much in demand in the past few years 
for making contrast studies of various 
parts of the circulatory system. The 
negatives are read as stills, although it 
is perfectly possible to copy them in 
sequence on motion picture film, and by 
repeating each negative frame three or 
four times on the print, to turn out a 
rather jerky motion picture. 5 

Cinefluorography 

The great majority of true x-ray 
motion pictures are made by method 3, 
generally known as Cinefluorography or 
indirect cineradiography. Here we have 
an economical and flexible technique for 
examining subjects of medium and large 
size at camera speeds up to 120 frames/ 
sec. The faults of the method are, 
first, a less favorable exposure factor 



Weinberg, Watson and Ramsey: X-ray Motion Pictures 



301 



a 




302 



October 1952 Journal of the SMPTE Vol. 59 



than that of direct cineradiography with 
screens, and second, a considerably 
greater degree of inherent unsharpness, 
as can be seen from the comparative 
figures given in Table I. It must also 

Table I. Exposure and Unsharpness* 

Characteristics of X-ray 
Motion Picture Techniques 

Relative 

exposure Unsharp- 

require- ness* or 

Method ment blur, mm 

1 . Direct cineradi- 
ography (without 

screens) 25.0 0.05 

2. Direct cineradi- 
ography (medium 

speed screens). . 1.0 0.3 

12 by 16 in. E2 

screen, //0.85 

lens, ortho film 2.0 6.0 

3. 35mm cinefluor- 
ography 10 by 13 
in. E2 screen, // 

1 .5 lens, ortho film 8.0 3.0 

4J by 6 in. D 

screen, //1. 5 

lens, ortho film 16.0 1.5 

* The unsharpness values listed above 
are offered as rough estimates and may 
contain a fairly large error. It is par- 
ticularly difficult to give a satisfactory 
overall unsharpness value for the 35mm 
frame because of the wide difference be- 
tween lens performance at the edge and in 
the center. For a constructive criticism 
of traditional sharpness and resolution 
measurements, see the recent paper by 
Higgins and Jones.6 

be admitted that the single-coated 
motion picture film is inferior in con- 
trast to double-coated screen-film. 
About the only remedy for this condition 
is the frequent use of a stationary grid 
to increase contrast by reducing scatter. 
If sufficient radiation could be brought 
to bear, it would no doubt be possible 
to make 35mm cinefluorographic records 
displaying nearly as much subject detail 
as 35mm reduction prints from full-scale 



screen-films. There is, however, an 
upper limit to the amount of continuous 
or near-continuous radiation that can 
be provided by the x-ray machine, and 
this limit must be further reduced when 
dealing with human subjects. Subject 
thickness, camera speed and length of 
examination in seconds must all be taken 
into account in budgeting permissible 
radiation, often leaving little room for 
the niceties of good copying. The 
desirably sharp tungstate intensifying 
screen, to which routine screen-films 
owe much of their excellent definition, 
is replaced in cinefluorography of adult 
human subjects by a faster, less sharp 
screen coated with relatively coarse 
crystals of zinc cadmium sulfide. Then 
the blurred image formed on the un- 
sharp screen is copied, blurs and all, by 
an ultrafast lens (definitely not a process 
lens) which in turn contributes addi- 
tional blur and flare of its own. 

As an illustration of what happens to 
fine subject detail under these extreme 
conditions we have reproduced side by 
side in Fig. 1 a full-scale screen-film and 
an enlarged 35mm frame taken from a 
cinefluorographic record. In this par- 
ticular case the improvement of 35mm 
definition, which could have been ob- 
tained by using a slower, better-cor- 
rected lens or a slower, sharper screen, 
was sacrificed in favor of a relatively 
high camera speed. Figure 2 shows the 
improvement of definition which results 
from using a sharp screen in close-up 
views. Curiously enough we have been 
unable to obtain any appreciable in- 
crease in sharpness by substituting a 
finer-grain film for the fast green- 
sensitive ortho film commonly used in 
cinefluorography. 

The //0.85 lens referred to in Table I 
is the 55-mm Zeiss R-Biotar originally 
designed for 16mm film, but used, for 
want of anything better, on several 
35mm cinefluorographic units including 
our own (Fig. 3). With this lens at 
full aperture, definition in the corners 
of the 35mm frame is frankly ter- 



Weinberg, Watson and Ramsey: X-ray Motion Pictures 



303 








i! 

w 

S g, 

1.2 



a B 






1 1 



V _ 

b ^ 



nfl 
t) 
en 





5 s 




s-s 
I" 

18 

<T5 "^ 

u 



304 



October 1952 Journal of the SMPTE Vol. 59 




Fig. 3. Left, Kodak f/0.81 43-mm focal length lens mounted on Cine Kodak 

Special. A popular f/1.5 lens is shown below for comparison. Right, Zeiss 

R-Biotar f/0.85 55-mm focal length lens mounted on 35mm camera. 




Fig. 4. New Kodak f/0.75 Fluro Ektar Lens designed for cinefluorography at a 
magnification of 1:16 (U.S. Patent 2,604,013). 



Weinberg, Watson and Ramsey: X-ray Motion Pictures 



305 



rible. The recent announcement of 
two new refracting lenses designed 
specifically for 35mm cinefluorography 
promises better definition than can 
be had from the 5 5 -mm R-Biotar, to- 
gether with an increase rather than a 
decrease of speed. The lenses are the 
Wray 65-mm //0.71 and the Kodak 
110-mm Fluro Ektar //0.75 (Fig. 4). 
Constructional details of the latter lens 
are described in the appended article 
by W. E. Schade. Both lenses are 
corrected for magnification of 1:16, 
that is, for a screen area a little smaller 
than 12 in. by 16 in. They should 
more than fill the place of the longer- 
focus Leitz and Zeiss //0.85 lenses, 
manufactured at one time for 35mm 
cinefluorography, but unobtainable since 
1940. 

X-ray Motion Pictures 
by Kinescope Recording 

The fourth method of making x-ray 
motion pictures has emerged as a by- 
product of recent experiments in fluoro- 
scopic screen intensification. Of the 
various image tubes and other devices 
which have been developed for this 
purpose the only one at present adaptable 
to motion picture work appears to be the 
Johns Hopkins apparatus demonstrated 
by Morgan 7 in 1950. In Morgan's 
intensifier the fluoroscopic image is 
picked up by a television camera fitted 
with an //0.7 Schmidt optical system of 
the "folded" type sometimes seen in 
television receivers. The reason for 
using such an extremely fast objective 
at the input end of the television ap- 
paratus is, of course, to make the most of 
the low brightness conditions prevailing 
on the fluorescent screen at average 
fluoroscopic x-ray intensities. It is now 
generally agreed that during fluoroscopy 
the near point on the subject's skin 
should not receive more than 10 r/min, 
a dosage rate frequently reduced to 
3 r/min or less by increasing filtration 
of the x-ray beam and using higher peak 
voltage across the x-ray tube. At these 



comparatively low intensities the bright- 
ness of the fluoroscopic image rarely 
exceeds 0.03 ft-mL (foot-millilamberts) 
in the highlights, and may fall below 
0.001 ft-mL in the shadows. That 
such an image can be picked up at all 
indicates the remarkable sensitivity of 
the image orthicon tube. 

As it appears on the kinescope, the 
intensified image of the subject is said 
to have an average brightness of about 
3 ft-mL, and is therefore, according to 
Morgan, from 300 to 3000 times brighter 
than the original fluoroscopic image. 
Like other kinescope images it can be 
copied at 30 frames/sec without resort 
to high-contrast film or lenses of aperture 
greater than //1. 5. 

By way of demonstrating the motion 
picture possibilities of his intensifier, 
Morgan has made a kinescope recording 
of a barium enema examination of a 
child of 7, covering about 3 min of 
action, 7 during which time the subject 
is said to have received a total skin 
dose of only 20 r. If it were attempted 
to record a similar examination by 
routine cinefluorography (//0.85 lens, 
E2 screen, stationary grid to reduce 
scatter, camera speed of 30 frames/sec), 
the total dose of 20 r would be reached 
in about 10 sec; in other words, only 
about 1/18 of the 3-min examination 
could be recorded. Of course, by re- 
ducing camera speed to 7.5 frames/sec 
(and repeating each negative frame on 
the print) the 10 sec of recorded action 
could be stretched to 40. Indeed, it 
would be possible by substituting the 
Fluro Ektar //0.75 lens for the //0.85 
R-Biotar to prolong the take to 50 sec, 
but even so a more than three-fold 
advantage would remain with the kine- 
scope record. 

As can be imagined from the number 
of glass and electron optical stages 
involved in x-ray kinescope recording, 
the motion picture films made by 
method 4 are not at present satisfactory 
from the point of view of detail. To 
what extent this condition can be im- 



306 



October 1952 Journal of the SMPTE Vol. 59 



proved remains to be seen. Certainly 
there is enough demand for better 
fluoroscopy, not to mention better 
image tubes and better television, to 
insure that the problem will not be 
neglected. 

References 

1. H. F. Sherwood, "Soft x-ray motion 
pictures of small biological specimens," 
Jour. SMPE, 28: 614-618, June 1937. 

2. R. Janker, "Roentgen cinematog- 
raphy," Am. J. Roentgenol. Radium 
Therapy, 36: 286, Sept. 1936. 

3. J. S. Watson and S. Weinberg, "An 
Improved Camera Drive for Cinefluorog- 
raphy," 1949. Multigraphed copies 
available from Department of Radiol- 



ogy, University of Rochester School of 
Medicine and Dentistry. 

4. W. G. Scott, "The development of 
angiocardiography and aortography." 
Radiology, 56: 485, Apr. 1951. (Para- 
graphs on radiographic equipment.) 

5. A. E. Barclay, K. J. Franklin and M. L. 
Pritchard, The Fetal Circulation, 
Charles C. Thomas, Springfield, 111., 
1945, Chapter 2. 

6. G. C. Higgins and L. A. Jones, "The 
nature and evaluation of the sharpness 
of photographic images," Jour. SMPTE, 
58: 277-290, Apr. 1952. 

7. R. H. Morgan and R. E. Sturm, "The 
Johns Hopkins fluoroscopic screen in- 
tensifier," Radiology, 57: 556, Oct. 1951. 

8. R. H. Morgan (an interview), "Now: 
motion pictures by x-ray," Johns 
Hopkins Magazine, 3: 14, Dec. 1951. 



Appendix: A New Kodak f/0.75 Fluro Ektar Lens* 
By W. E. Schade 



The new Kodak Fluro Ektar lens, 
f/0.75 of focal length 110 mm designed 
for 35mm cinefluorography at a magnifi- 
cation of 1:16, can be described as an 
extended modification of the classical 
example of simplicity, the Cooke triplet, 
to which a negative field-flattening ele- 
ment located near the focal plane has 
been added. Alternatively, the system 
could be regarded as a modified Cooke 
triplet to which a telephoto system has 
been attached. 

However, since simplicity and the 
application of a field-flattening element 
have been the leading motives in the 
design of the lens, the following detailed 
explanations will pertain to the first 
description. 

The//0.75 Fluro Ektar lens consists 
of seven glass elements, two of which are 
made of the new high-index glasses 
developed and manufactured by East- 
man Kodak Co. (Fig. 5). 

The Appendix was contributed in June 
1952 by W. E. Schade, Hawk-Eye Works, 
Eastman Kodak Company, Rochester, 
N.Y. 

*U.S. Patent, 2,604,013, Aug. 8, 1951. 



The first two elements (1 and 2) are 
of collective power. These are followed 
by a hyperchromatic component of dis- 
persive power. The negative element 
(3) of this component is made of a 
highly dispersing flint glass, whereas 
the other element (4) of this component 
consists of one of the new high-index 
glasses mentioned above. The proper- 
ties of these two glasses, namely, nearly 
equal high indices of refraction for the 
D line, but widely differing dispersions, 
have made it possible to simplify the 
achromatization of the new lens. 

Elements 5 and 6 are again of collec- 
tive power, element 6 being made of 
one of the new high-index glasses. 

The arrangement of these six elements, 
as shown in Fig. 5 produces a focal length 
of 106.4 mm and the marginal ray 
emerges at an aperture of //0.64. 

Finally, the field-flattening element 
(7) of dispersive power, located near the 
focal plane, then extends the focal 
length to 110 mm and reduces the aper- 
ture to f/0.75 as required. 

The results of this relatively simple 
design are such that the lens will render 



Weinberg, Watson and Ramsey: X-ray Motion Pictures 



307 




Fig. 5. Cross section of Kodak f/0.75 Fluro Ektar Lens of 110-mra focal length 
designed for 35mm cinefluorography (U. S. Patent 2,604,013). 



highly satisfactory performance in many 
applications. The spherical aberra- 
tions have been reduced to an extreme 
minimum. Astigmatism and curvature 
of field are practically eliminated and 
the distortion (barrel) is negligible. 
The color corrections, longitudinal as 
well as lateral, are also fulfilled. 

The dimensions of the system at a 
magnification of 1:16 are as follows : 

Distance from screen to 

image plane 2023 . 1 mm 



Object distance (from 

screen to first surface 

of lens 1807.8mm 

Image distance (from last 

surface to image plane) . 7.3 mm 
Length of lens (from first 

to last surface) .... 208 . mm 
Diameter of front aperture . 143.2mm 
Since preliminary tests have proved 
the exceptionally satisfactory perform- 
ance of the lens, it is anticipated many 
applications for it will be found in 
other fields. 



308 



October 1952 Journal of the SMPTE Vol. 59 



A Precision Color Temperature 
Meter for Tungsten Illumination 

By G. H. DAWSON, D. E. GRANT and H. F. OTT 






A precision color temperature meter utilizing red and blue filters is described. 
A special logarithmic diaphragm largely eliminates undesirable effects of 
nonuniform response over the cell area and aids accurate setting of the red 
filter standard at high intensities. 



A OR MOST VISUAL or photographic 
purposes extremely accurate measure- 
ments of color temperature are not 
necessary. In the film industry, how- 
ever, color films must be evaluated 
carefully to determine specifications 
which will, under proper conditions of 
exposure and processing, result in 
uniformly good color balance. Conse- 
quently, to remove test variability as 
much as possible, it is necessary to know 
and control within relatively close 
limits the color temperature of the 
tungsten lamps. A red-blue ratio is used 
as an index of color temperature since 
the radiation from a tungsten lamp 
follows closely the spectral energy dis- 
tribution of a blackbody. 

It was found that the variability 
within available meters was greater 
than the allowable tolerances of the 
tungsten source itself for testing purposes. 
Such a relatively high instrument vari- 
ability would not assure a sufficiently 

A contribution submitted July 21, 1952, 
by G. E. Dawson, D. E. Grant and H. F. 
Ott, Color Control Div., Eastman Kodak 
Co., Rochester 4, N.Y. 



reliable determination of color tempera- 
ture. 

Variability in most commercially 
available meters can be attributed to: 

1. Differential diffusion of blue and 
red light and vignetting. These errors 
are most serious when the light is off 
axis or when an extended source is used. 

2. Nonuniformities in response from 
one area to another of the cell, giving 
different effective color temperature 
readings at different intensities of illumi- 
nation. 

3. Difficulties in adjusting the instru- 
ment to the red filter standard at high 
intensities where the aperture over the 
cell is small and its area is changing 
rapidly when a direct linear diaphragm 
is used. 

4. A trigger arrangement for shifting 
filters which moves the entire instru- 
ment when actuated. 

Description 

An improved color temperature meter, 
Fig. 1, utilizing red and blue filters has 
been designed by the authors to give the 
needed precision. Most important to 



October 1952 Journal of the SMPTE Vol. 59 



309 




Fig. 1. Color Temperature Meter. 



the increased precision is a specially de- 
signed diaphragm which allows incident 
light to be distributed over the cell 
surface at either high or low intensity. 

The essential elements of the instru- 
ment, labeled to correspond to Fig. 2, 
are: 

a. The diffuser 
c. The special diaphragm 
b, d. Filters 

f. Trigger arrangement for 

switching filters 
e. Photronic cell 
i. Meter 

g, h. Handle, including tripod 
socket 

In use, the color temperature meter is 
pointed directly at the source to be 
measured and the diaphragm ring ro- 
tated until a standard reading is ob- 
tained on the microammeter through the 
red filter. The trigger is then depressed 
and a second reading is obtained through 
the blue filter. The color temperature 



of the source can then be read from a 
calibration curve. A scale could be 
inscribed on the microammeter reading 
directly in color temperature. 

Diffuser, Cell and Meter 

To keep the angular acceptance large, 
as well as to maintain accuracy of the 
instrument, an opal diffuser was put at 
the extreme front of the instrument. 
The metal parts, other than the dia- 
phragm, were arranged so they could 
cause no shadowing of the cell. In 
addition, the diffuser-to-cell distance 
was made as small as possible. The 
diffuser chosen was an opalized cellulose 
acetate on glass support. To remove 
any effects of the blue-red diffusion 
differential of the opalized glass, a pale 
blue filter was placed between the 
diffuser and the diaphragm. Areas of 
the filter are cut away so that it gives 
maximum compensation when the dia- 



310 



October 1952 Journal of the SMPTE Vol. 59 



rfjn 





a Diffusing Disk 
b Correction Filter 
c Diaphragm Leaves 
d Red and Blue Filters 
Photronic Cell 
Trigger Assembly 
Handle 

Tripod Socket 
D-C Microammeter 



Fig. 2. Schematic side view of Color Temperature Meter. 



.gm openings are large, but none 
when they are small. 

The cell used in the instrument is a 

! Type 3RR Weston Photronic Cell 

especially selected for low fatigue at 

both ends of the visual spectrum. The 

' meter is Model 731 Weston to 30 

microammeter. 

Diaphragm 

The special diaphragm (Fig. 3) 
utilizes six leaves (a), three on each side 
' of a thin center plate (b) which by rota- 
i tion causes the leaves to move over the 
j aperture or away from it. The leaves 



and actuating disk are between two 
outer plates. These plates support the 
pins on which the pivot ends of the 
diaphragm leaves can rotate. The dia- 
phragm leaves have long, narrow tongues 
which at full open position extend across 
the circular diaphragm opening dividing 
it into six pie-shaped openings. Since 
the support pins for the leaves are 
spaced at 60 intervals alternately in 
one support plate then the other, the 
tongue of one leaf at full open aperture 
overlays the tongue of a leaf on the 
opposite side of the actuator. 



Dawson, Grant and Ott: Color Temperature Meter 



311 




Fig. 3. Color Temperature Meter dia- 
phragm. 

The means of moving a leaf is a 
headed pin through a cam slot (c) in 
the diaphragm leaf into the center 
actuating member. As this member 
is rotated to close the diaphragm, each 
leaf moves inward, rotating about its 
support pin, the rate being controlled 
by the cam slots which are cut so that 
the logarithm of the open area of the 
diaphragm is proportional to the angle 
of rotation of the actuating ring. The 
logarithmic-type diaphragm ring facili- 
tates accurate setting of the constant 
red filter reading regardless of light 
intensity. The leaves are so shaped 
that the pie-shaped openings first narrow 
abruptly as the diaphragm is closed, 
then gradually change shape to form six 
equally-spaced diminishing cat-eyes. 
The undesirable effects of nonuniform 



response over the cell area are thus 
largely eliminated. 

Filters and Trigger Mechanism 

The filters used were Kodak Wratten 
Nos. 38 A and 29. These were so 
mounted that a thumb-actuated trigger 
mechanism replaced the red filter 
normally in the beam with the blue 
filter. The thumb-actuated trigger 
causes less instrument motion than a 
finger-actuated trigger. The handle, 
in the side of which the trigger is located, 
is shaped to fit the hand and is under 
the center of gravity of the instrument. 
It also includes a tripod socket for 
critical measurements. Although the 
instrument is accurate with illumination 
off axis, its sensitivity to intensity varia- 
tions is still sufficiently critical so that 
care must be exercised to move the 
instrument as little as possible. 

Precision 

The color temperature meter was 
calibrated against 1000- and 1500-w 
lamps at 200 to 1000 ft-c. The pre- 
cision of the instrument as normally 
used is =t 5 K. As the angle of illumina- 
tion increases from 30 off axis to the 
angle at which a reading can no longer 
be obtained, the precision decreases 
gradually to 10 K. The accuracy is 
dependent chiefly upon the validity of 
the calibrations of the lamps used as 
standards. 



312 



October 1952 Journal of the SMPTE Vol. 59 



Comparison of Recording Processes 



By JOHN G. FRAYNE 



The three common forms of sound recording may be classed as mechanical 
(disk), photographic and magnetic. All three methods are in common use 
today and each is employed in a field for which it appears to be peculiarly 
fitted. The purpose of this article is to examine briefly the factors which 
determine the fidelity of each method. By fidelity we mean how true the 
tonal range can be reproduced, the amount and nature of harmonic distortion 
present, the signal-to-noise ratio possible with each method, and the amount 
of wow or flutter that may be expected under average conditions of repro- 
duction for each recording process. 



Disk Recording 

Although there are other methods of 
mechanical recording, such as embossing, 
we shall confine our discussions on me- 
chanical recording in this article to the 
well-known circular flat disk method. 
This type of recording remains the most 
popular form for home entertainment 
and is widely used in transcription radio 
programs. One characteristic that 
differentiates disk recording from the 
other methods is the comparatively 
higher mass of the moving parts involved 
in making and reproducing the record. 
The disk material must actually be cut 
with a stylus having a high degree of 
stiffness and a comparatively high mass. 
Likewise on reproduction, disk record- 

A technical editorial by John G. Frayne, 
Westrex Corp., 6601 Romaine St., Los 
Angeles 38, Calif. Reprinted by per- 
mission of the Editor of The Institute of 
Radio Engineers, from Transactions of the 
IRE, Professional Group on Audio, PGA 6: 
Mar. 1952, and PGA 7: May 1952. 



ing involves the movement of a repro- 
ducing stylus which in itself must have 
considerable stiffness and mass. In 
disk recording, the resonant frequency 
of the recorder is usually considerably 
below the highest recorded frequencies. 
Since this necessitates recording through 
the resonant range of the recorder, a 
high degree of damping must be em- 
ployed to remove the resulting resonant 
peak. This damping, whether supplied 
by mechanical means or electromagneti- 
cally through some sort of feedback sys- 
tem, results in a velocity of the recording 
stylus which is constant and independent 
of the frequency for a constant applied 
force. This type of recording is known 
as constant velocity and with the addi- 
tion of pre-emphasis in the recording 
circuit is widely used in cutting present- 
day high-quality records. 

Since the amplitude of the cut for a 
constant applied force is inversely pro- 
portional to the frequency in a constant 
velocity recorder, it is customary to 
record the lower frequencies or longer 



October 1952 Journal of the SMPTE Vol. 59 



313 



wavelengths on a more nearly constant 
amplitude basis. This limits the ampli- 
tude of the cut at the lower frequencies. 
The frequency at which the change- 
over is made is usually referred to as 
the crossover point. In cheaper re- 
corders, this presents no problem, but 
in the higher-quality feedback-type re- 
corders, this has to be done by appro- 
priate recording equalization. With the 
best type of feedback cutters, good 
records may be recorded out to 12-15 
kc, whereas on the cheaper types 5 or 
6 kc is a desirable upper limit. When 
a constant velocity record is reproduced 
with a variable reluctance type of re- 
producer, a constant voltage results. 
For those parts of the spectrum cut at 
constant amplitude, reproducing equali- 
zation complementary to that used in 
recording must be used. 

Like all recording media, disk re- 
cording is subject to its own peculiar 
types of distortion. One of the most 
common forms of disk distortion is 
brought about by the fact that a sinus- 
oidal wave cut into the record must 
be tracked in reproduction by a stylus 
of finite radius of curvature. It is ob- 
vious that at short wavelengths it is 
impossible under such conditions to 
reproduce a true sinusoidal response. 
Instead, a series of poids result which, 
in the case of the more common lateral 
type of disk recording, produce odd- 
order harmonic distortions. Since the 
wavelength for any given frequency 
diminishes as the groove diameter of 
the disk is reduced, such distortion 
increases rapidly with diminishing 
diameter for any given impressed fre- 
quency. This has been studied in 
detail by Pierce and Hunt and they show, 
for example, that in 33^-rpm records, 
distortion at 5000 cycles may amount 
to as much as 30% for an 8-in. diameter, 
dropping to as low as 2% for a 16-in. 
diameter. Similarly for 78-rpm records 
for the same frequency, distortion may 
amount to 20% for a 4-in. diameter 
and drop to approximately 1% for a 



12-in. diameter. It is this factor which 
limits the effective inner diameter on 
33^-rpm microgroove records to 5 in. 
and on 45 rpm to 3f in. Accompany- 
ing this increasing distortion as the 
groove diameter is reduced is a corre- 
sponding loss in high-frequency response. 
This may be corrected to a certain 
degree by introducing variable equaliza- 
tion in recording, increasing the high- 
frequency input to the cutter as the 
groove diameter is reduced. While 
this may correct for high-frequency re- 
sponse, it only adds to the distortion 
resulting at the higher inputs. 

Another form of distortion in re- 
producing from disk records is known as 
tracking distortion. This is brought 
about by the fact that since the re- 
producer is supported by a pivoted arm, 
the angle which the axis of the stylus 
makes with the groove is constantly 
changing as the reproducer moves 
across the record. This form of dis- 
tortion is very complicated and results 
in the generation of both even and odd 
harmonics. This tracking error can 
be reduced to a minimum by proper 
design of the reproducing arm. 

The commonly used expression "wow" 
to denote low-frequency speed varia- 
tions in sound reproduction had its 
origin in the once-per-revolution speed 
variation (wow) of cheap disk turn- 
tables. At 78 rpm this corresponds to 
a frequency of 1.3 cycles/sec, a rate 
at which the ear is extraordinarily 
sensitive to pitch changes. This low- 
frequency rate is a difficult one to 
correct in a mechanical system without 
resort to very expensive and accurate 
drive systems which are completely 
beyond the range of the home pocket- 
book. The problem is further aggra- 
vated by the provision for three speeds 
in many turntables, each of which may 
call for somewhat different corrective 
mechanical filtering. In the profes- 
sional field, the problem of wow has been 
largely overcome and flutter less than 
0.1% may be attained. 



314 



October 1952 Journal of the SMPTE Vol. 59 



Another factor which has limited 
high fidelity in disk reproduction has 
been the so-called needle scratch. This 
has been accented by the use of the older- 
type shellac records carrying an abrasive 
for grinding the steel reproducer needle 
to match the groove. This condition 
has been greatly improved in recent 
years by the adoption of improved pres- 
sing materials such as acetate or Vinylite 
and the wide adoption of permanent- 
type needles. For home use, a signal- 
to-noise ratio of the order of 40 db is 
probably adequate, but for professional 
use this should be improved to at least 
50 db. A further improvement in 
signal-to-noise ratio is the recent adop- 
tion of the so-called hot stylus technique 
in recording. This method usually 
results in an improved signal-to-noise 
ratio especially at the inside area of the 
disk. Simultaneously, it appears to 
result in improved high-frequency re- 
sponse. 

When one considers the mechanical 
nature of disk recording and reproduc- 
tion and the fact that a plastic with its 
cold flow and general instability has 
to be employed, the resulting fidelity 
in modern disk recording may be con- 
sidered a triumph of research in indus- 
trial design and manufacture. When 
one further takes note of the various 
processes which are followed in going 
from an original acetate cut record 
through the plating and stamping 
processes, one is further impressed at 
the really excellent job that can be done 
in modern disk recording. 

Photographic Recording 

Under ideal conditions of recording, 
processing and reproduction, modern 
photographic recording offers a medium 
of high-fidelity sound reproduction the 
equal, if not superior, to that of any 
other method. Two well-known 
methods variable-density and vari- 
able-area are in wide use in photo- 
graphic recording. With accurate con- 
trol of film processing, extremely high 



fidelity records may be obtained for 
both variable-density and variable-area 
methods. In the professional 35mm 
field, such controls are successfully used 
with a resulting high-quality product. 
In the lower-cost 16mm field, it is a 
matter of regret that much improve- 
ment is still awaited in this regard. 
Over the years since photographic re- 
cording was first introduced, there has 
been a vast improvement in the type of 
photographic emulsions suitable for 
both density and area recordings. Re- 
cording devices and light-modulating 
systems have been brought to a point of 
near perfection, and the general improve- 
ment in the electronic art has contributed 
to practically distortion-free film and 
reproducing systems. 

A method of reducing background 
noise unique to photographic recording 
is the universal use of bias or noise- 
reduction recording in which the average 
transparency of the sound track varies 
with the envelope of the sound wave- 
form. This results in a minimum of 
film grain noise and photocell hiss for 
the low-level passages and automatically 
permits a rise in these unwanted noises 
as the signal amplitude increases. 

The most difficult problem to overcome 
in photographic recording has been 
the development of high-quality trans- 
port of the film past the point of optical 
translation. The earlier film recorders 
were subject to much wow and flutter 
with disturbing rates varying all the 
way from 1 cycle/sec to 96 cycles/sec, 
the latter corresponding to the sprocket- 
hole frequency of 35mm film. As a 
result of much research into the nature 
of flutter, improved designs of pro- 
fessional 35mm recorders and repro- 
ducers have been introduced in recent 
years which are remarkably free from 
flutter. Today, a photographic re- 
corder with a total flutter content 
exceeding 0.1% would have difficulty 
finding any market. In 16mm photo- 
graphic recording, due to the slower 
speed employed, it is more difficult to 



John G. Frayne: Comparison of Recording Processes 



315 



secure equally good film movement. 
This is only too obvious in the reproduc- 
tion of many 1 6mm sound tracks heard 
over television programs. As a conse- 
quence, high-quality 16mm film re- 
corders should call for more careful 
design and construction than the more 
professional 35mm types. The con- 
trary, however, has usually been the 
result, due to the poorer economic 
status of 16mm. The same comment 
holds even more true for 16mm re- 
producers. Instead of the sturdy pro- 
fessional-type 35mm theater reproducers, 
the 16mm field has until quite recently 
been content to use lightweight, portable, 
flimsily built 1 6mm reproducers to meet 
a highly competitive market condition. 
Recently, due to the wide use of 16mm 
film in television, there have appeared 
several professional 16mm reproducers 
which tend to overcome this difficulty. 

At the standard speed of 18 in. /sec 
for 35mm, the practical upper limit to 
frequency response is around 8-10 kc. 
This limit is the result of recording and 
printing high-frequency losses as well 
as the losses introduced by the use of a 
finite scanning slit in reproduction. 
This has been recognized by the motion 
picture industry in limiting frequency 
response of theater systems to approxi- 
mately 8 kc. In the 16mm field where 
the film speed is only 40% that of 35mm, 
it is much more difficult to secure a 
wide frequency response. It is only by 
resort to considerable equalization in 
recording and reproducing that satis- 
factory response to 6 kc may be made. 
This inevitable shortcoming of 16mm 
recording results in the well-recognized 
"chesty" nature of the sound. 

The limiting factor in the signal-to- 
noise ratio in film recording is the 
background noise produced by the 
graininess of the photographic image 
and also by the accumulated dirt and 
scratches on the film. This usually 
limits photographic tracks to a usable 
signal-to-noise ratio of around 40 db, 
although new tracks employing fine- 



grain films and noise-reduction tech- 
niques may give a value of at least 50 db. 
Even though an excellent photo- 
graphic track may be obtained from the 
film processing laboratory, the final 
result may be considerably affected by 
the reproducing mechanism. Flutter 
in the reproducer will produce results 
equally as disastrous as those from poorly 
made film recorders. Considerable dis- 
tortion, especially in the variable-area 
system, may be encountered by non- 
uniformity of the scanning beam in the 
reproducer and even more seriously by 
failure to have the reproducing scanning 
beam in the correct azimuth. Other 
limitations in reproducing, especially 
in 16mm, are low-cost amplifier systems 
which do not have sufficient output 
capacity for the higher-level passages 
on the film and insufficient hum filtering 
which in many cases permits an audible 
60-cycle reproduction from the loud- 
speaker. In the matter of loudspeakers, 
the photographic system probably fares 
better than either of the other two 
methods. There has been a vast im- 
provement in loudspeakers in profes- 
sional 35mm theaters. This cannot be 
said, however, for the speakers used in 
the lower-cost portable 16mm repro- 
ducing systems. 

Magnetic Recording 

In common with the other recording 
techniques discussed above, magnetic 
recording is also affected by uneven 
motion of the magnetic tape or film in 
the recorder and reproducer. The ex- 
treme flexibility of the standard J-in. 
tape aids considerably in simplifying 
the tape-pulling mechanism and it is 
possible to obtain considerable freedom 
from very low flutter rates with a rela- 
tively inexpensive drive. The common 
capstan-type drive usually introduces 
low-frequency flutter rates which, how- 
ever, are considerably higher than those 
encountered in disk recording and are, 
therefore, not so objectionable to the 
ear. Magnetic recording, however, does 



316 



October 1952 Journal of the SMPTE Vol. 59 



introduce a considerable amount of 
high-frequency flutter of a somewhat 
random nature which may be traced to 
the irregular motion of the tape or film 
over the magnetic head. Fortunately, 
these rates are sufficiently high so that 
their effect on the ear is negligible 
except at the higher audiofrequencies 
such as some of the higher overtones 
from string instruments. This irregular 
motion of the tape over the magnetic 
head also introduces considerable ampli- 
tude distortion which produces an effect 
almost indistinguishable from that of 
the high-frequency flutter. Thus, at 
the commonly accepted speed of 15 
in. /sec, both of the effects produce a 
very harsh quality if the sound spectrum 
is pushed up to the 1 5-kc limit. 

Magnetic tape recording utilizing the 
high-frequency bias may be reproduced 
with a minimum of distortion which is 
generally lower than that in either disk 
or photographic recording. At the same 
time, a signal-to-noise ratio of 50 to 
60 db may be obtained. This, however, 
calls in recording for a very high- 
quality, high-frequency bias oscillator 
with a second harmonic content about 
60 db lower than the fundamental. 
The ratio of the high-frequency current 
to the maximum audio current must be 
of the order of 10 to 20. To achieve 
the low noise level and relative freedom 
from distortion, extreme care must be 
taken to insure that the magnetic head 
and associated shield do not acquire 
any permanent magnetism, as the d-c 
magnetic field thus produced acts in a 
manner directly analogous to the pres- 
ence of second-order harmonic com- 
ponents in the high-frequency bias 
oscillator. One common result of these 
d-c fields is a pronounced rumble in 
reproduction. This same effect may 
also be traced to improperly erased 
tape. With the proper value of high- 
frequency bias for any given magnetic 
head and tape, the distortion above the 
so-called overload of the medium is 
mostly third-order harmonic compo- 



nents, the second-order being almost 
entirely absent. Experience has shown 
that considerable overload may be 
tolerated and this is generally attributed 
to the absence of the more unpleasant 
even-order harmonic components. A 
disturbing factor in J-in. tape is the 
presence of so-called "print-through" 
from layer to layer, resulting in what 
appears to the listener as an echo. 
This can be prevented by reducing peak 
amplitudes in the recording and may 
be prevented from becoming too serious 
by avoiding storage of recorded tape in 
excessive high -temperature locations or 
in the proximity of high magnetic or 
electrostatic fields. 

The frequency response from magnetic 
film recorded at constant current input 
to the recording head increases at a 6 db 
per octave rate over a considerable 
portion of the audio spectrum. It then 
flattens off and begins a fairly sharp 
decline. This dropping off at the 
upper frequencies results from two 
causes one, demagnetization in re- 
cording at the shorter wavelengths; 
and two, the scanning losses which are 
directly analogous to those found in film 
reproduction. For a 0.5-mil reproduc- 
ing gap and speed of 15 in./sec, this fall- 
off in high-frequency response begins 
in the neighborhood of 2000 to 3000 
cycles. It is customary to correct for 
the 6 db per octave slope by inserting 
a simple RC correcting network in the 
reproducing circuit, and a fairly flat 
response may be obtained down to 
approximately 100 cycles by this simple 
expedient. Below this point, irregu- 
larities in low-frequency response are 
frequently encountered, and more com- 
plicated means of equalization must be 
employed if these are to be smoothed 
out. To insure a wider, higher fre- 
quency response, equalization must be 
used and it is customary to do this 
partly in recording and partly in re- 
producing. As pointed out above, a 
tape speed of 1 5 in./sec in response may 



John G. Frayne: Comparison of Recording Processes 



317 



be made fiat out to approximately 1 5 kc 
without resort to excessive equalization. 
One of the problems peculiar to 
magnetic recording is the care that 
must be taken to avoid excessive 60- 
cycle hum pickup in the reproducer. 
Since the common power-line frequency 
of 60 cycles may have a gain 20 to 30 
db higher than say 1000 cycles in order 
to correct for the nonlinear frequency 
response referred to above, the pickup 
head and the input circuit, especially the 
input transformer of the preamplifier, 
must be well shielded to avoid pickup 
from ambient 60-cycle fields. For- 
tunately, the well-known ear charac- 
teristic for medium sound reproducing 
levels aids in reducing the effect of such 
a disturbing frequency. The ear's being 
at least 20 db less sensitive at this fre- 



quency than at a 1000-cycle tone means 
that an effective signal-to-noise ratio 
of 40 db at 60 cycles will be equivalent 
to a 60-db signal-to-noise ratio at the 
higher frequency. 

In conclusion, we may note that all 
three media have their own particular 
factors that limit their fidelity. When 
all factors including economic are taken 
into consideration, the magnetic medium 
appears to offer the greatest possibility 
of high-quality sound reproduction with 
a minimum investment in recording and 
reproducing equipment. The re-use ol 
the tape and the general simplicity of 
operation are other factors which seem 
to be responsible for the remarkably 
wide use of the magnetic medium in the 
very short period since its general intro- 
duction in this country. 



318 



October 1952 Journal of the SMPTE Vol. 59 



A Building-Block Approach to 
Magnetic Recording Equipment Design 

By KURT SINGER and J. L. PETTUS 



The requirements of magnetic recording equipment for sound motion pictures 
have been found to vary greatly with different customers. In order to pro- 
vide the necessary flexibility to meet these different requirements and to 
include various custom features, the functional units of a magnetic recording 
channel have been designed on separate rack-mounted panels which can be 
installed in varying arrangements in a standard amplifier rack. These include 
items for both single-track and three-track equipments, and film widths of 
16mm, 17. /mm and 35mm. 



T, 



HE EQUIPMENT required for a sound 
recording plant varies widely depending 
on the type of recording, the size of the 
associated studio, and the magnitude of 
the plant operation. In this respect 
magnetic recording or reproducing 
equipment differs in considerable detail 
over its predecessor, photographic re- 
cording and reproducing equipment. 

i In the latter case, certain facilities were 
necessarily reserved for photographic 

f film handling. These included dark 
rooms, film magazines and lighttight en- 
closures in the recording facilities. In 
contrast, magnetic equipment offers some 
consolidation in plant layout as well as 
certain conveniences in operation. 

Presented on October 18, 1951, at the 
Society's Convention at Hollywood, Calif., 
by Kurt Singer and J. L. Pettus, Radio 
Corporation of America, RCA Victor Div., 
Engineering Products Dept., 1560 N. Vine 
St., Hollywood 28, Calif. 



The requirements of magnetic record- 
ing/reproducing equipment for sound 
motion pictures have been found to vary 
greatly with different installations. 
These requirements plus the fact that 
many studios will wish to install mini- 
mum equipment at the beginning and 
"grow" with the development of mag- 
netic recording, led the authors to the 
conclusion that studio equipment should 
be made of carefully planned units so 
coordinated that they could be easily 
fitted together to provide almost any de- 
sired combination of equipment layout. 
This is essentially the "building block" 
idea which is today employed in many 
types of industrial apparatus. Thus, 
when expanding a system such as from a 
few magnetic recording channels to a 
more comprehensive system or from a 
single-track to a triple-track recorder/- 
reproducer, it is not necessary to add 
entirely new recorder mechanisms but 
rather to increase the number of compo- 



October 1952 Journal of the SMPTE Vol. 59 



319 




320 



October 1952 Journal of the SMPTE Vol. 59 



nents as desired. Moreover, this is 
readily possible if all of the component 
assemblies have been designed to mount 
on a standard relay cabinet rack or 
equivalent having the industry standard 
multiple dimensioning. The three sys- 
tem layouts described in the following 
text have been chosen to illustrate the 
wide range of equipment combinations 
which are practical. For the most part, 
these are actually in use or are now being 
installed in several large motion picture 
studios. 

Of the different equipment combi- 
nations to be described, types A and B 
utilize a single magnetic track while type 
C provides three sound tracks having all 
tracks recorded and/or reproduced 
simultaneously and positioned in accord- 
ance with Motion Picture Research 
Council proposed standards. 1 

Basic Mechanical Arrangement 

There are several ways of arranging 
components in the vertical plane but 
these generally follow the rules of hand 
and eye levels for those items requiring 
the greatest amount of operation atten- 
tion. An example of a single-track mag- 
netic recorder/reproducer channel is 
shown in Fig. 1 and identified as RCA 
type PM-66 equipment. Here the ex- 
treme upper portion of the rack supports 
the bias oscillator/preamplifier followed 
by a film-feed assembly, a control panel, a 
1 film-drive mechanism, a film take-up 
assembly after which are located power 
supplies and other miscellaneous audio 
components. Figure 2 shows a number 
of these units assembled in line for a 
multiple-channel installation, yet with 
each unit being capable of independent 
operation. 

Figure 3 shows a type B arrangement 
for application where it is desirable to 
reduce the vertical height of the mechani- 
cal components to a minimum. Here 
the controls have been relocated on the 
film-feed assembly to conserve space. 
As in the type A equipment, the audio 



components are located above and below 
the mechanical units and positioned as 
to their operating convenience. 

Type C equipment is shown in Fig. 4 
as an arrangement which provides a 
three-track magnetic recorder/repro- 
ducer channel and is identified as RCA 
type PM-63 equipment. Here it was 
necessary to assemble all audio compo- 
nents in two racks and all mechanical 
components in a third rack. All racks 
are tied together to form a single and 
complete unit assembly. Such an ar- 
rangement provides for maximum serv- 
iceability to all elements but occupies 
bnly minimum plant space. Here again 
many components as shown in Fig. 1 are 
used with only minor alteration to the 
film-drive mechanism for the number of 
magnetic-head assemblies employed. 

Selection of component assemblies in 
practice follows the requirements and 
specifications for a given installation. 
To begin with, the width of the recording 
medium, the number of magnetic tracks 
per channel and the required film ca- 
pacity determine the basic elements. In 
general, the width of the film does not 
alter the basic design except for the 
physical size of certain parts and the 
speed of the film-driving mechanism. 
This latter difference has been chiefly 
limited to the use of 1 6mm film operating 
at 36 fpm and 17-| or 35mm film operat- 
ing at 90 fpm. However, in view of fur- 
ther economy in magnetic recording, the 
use of 17^mm film operating at 45 fpm 
for all original or production recording, 
is gaining favor in the industry. Mag- 
netic recording equipment for 45 fpm 
operation was presented before this So- 
ciety in a paper entitled "A Technical 
Solution to Magnetic Recording Cost 
Reduction." 2 

The number of magnetic tracks regard- 
less of the width of the film has been pri- 
marily limited to the use of a single track 
on all widths for production recording 
and triple tracks on 35mm film in dub- 



Singer and Pettus: Magnetic Recording Equipment 



321 




Fig. 4. Triple-track rack assembly, Type C equipment. 



bing or re-recording operations. Of 
course, there are many possibilities of 
using a plurality of tracks on either of the 
other two film widths. 

Description of Mechanical Components 

A. Film Feed and Take-up Assemblies. A 
panel of approximately 1 5f in. high will 
accommodate a film capacity of 2000 ft. 
This size was chosen as being most satis- 
factory in the majority of installations. 
In the past, many recorder /reproducer 
designs have used a rather simple friction- 
type clutch as an integral part of the feed 
and take-up assemblies to tension or wind 
the film on the respective film reels. The 
applied tension between start and finish 
pay-out or take-up of a 2000-ft-roll of 
35mm film wound on a 2-in. diameter 
core, was found to vary by a ratio of 1 : 8 
under average operating conditions. 



Such a variation reflects an undesirable 
condition to the film-drive mechanism. 
Furthermore, the desire to incorporate 
rewinding from reel to reel as a feature on 
new equipment is well founded. 

These two factors guided the design to 
make use of a torque-type motor to serve 
as a tensioning device having a nearly 
linear characteristic for both holdback 
and take-up as well as being suitable for 
a high-speed rewind. The first function 
was obtained by applying varying poten- 
tial to the motor in proportion to the 
amount of film on the reel and phased for 
rotation opposite that of the film pay-out. 
This provided an ideal holdback system. 
Similarly, it also provides an ideal 
take-up system except that rotation of 
the torque motor must agree with the 
direction of film winding and have some- 
what greater torque. The third function 



322 



October 1952 Journal of the SMPTE Vol. 59 



R-l 



MASTER SWITCH REVERSE 




Fig. 5. Schematic of torque motor voltage controller. 



as a rewind was obtained by using the 
motor at its rated output as a propulsion 
device. The electrical elements of this 
assembly are shown schematically in Fig. 
5. From this, it will be noted that the 
use of a variable series resistance (R-l) in 
one leg of a single-phase motor, serves to 
vary the motor torque for either hold- 
back tension or forward torque for 
take-up. The resistor (R-l) is varied by 
a commutator (S-l) by means of a fol- 
lower arm in contact with the periphery 
of the film roll. Additionally, a relay 
(K-l) is used to vary the overall torque 
curve when the motor is functioning for a 
take-up instead of a holdback as in the 
case of reverse operation. This relay is 
normal in the holdback function and 
energized by the master control switch 
for the reverse or take-up function. As 
shown in Fig. 5, the commutator switch 
(S-l) is in its initial position at the maxi- 
mum film roll diameter thus placing the 
least amount of R-l in series with a sec- 



ond resistor (R-2) and this combination 
being seen by one leg of the torque motor. 
As the commutator switch progresses 
with a decrease in film roll diameter, sec- 
tions of R-l are automatically added, 
proportionally reducing the motor 
torque. As the last two steps are 
reached, R-l is opened allowing only the 
inherent load of the motor-drive assem- 
bly to serve as friction in the holdback 
function, these two steps being at diam- 
eters less than 5 in. When functioning as 
a take-up device, relay K-l becomes 
energized and shorts out R-2 to increase 
the overall torque range. Additionally, 
steps 1 and 2 of S-l are seen by R-l, thus 
giving a potential to the motor at the 
minimum or starting diameter of the 
take-up roll. Controlling the torque of 
each motor by the described method pro- 
duced a film tension characteristic con- 
stant within 2 oz throughout the length 
of a 2000-ft reel using a 2-in. OD core. 



Singer and Pettus: Magnetic Recording Equipment 



323 




Fig. 6. Film-drive mechanism. 



As an operating convenience, the fol- 
lower arm is automatically retracted from 
the film reel by means of a solenoid ener- 
gized through the master control switch 
when positioned at OFF. Upon setting 
the master switch for the desired oper- 
ation of the film drive, the follower arm is 
released and allowed to seek the periph- 
ery of the film roll. Thus, a predeter- 
mined potential to the torque motor is 
automatically established. 

B. Control Panel Assembly. As shown in 
Fig. 1, controls for the film-drive mech- 
anism, as well as for rewinding, are 
mounted on a separate panel. An ex- 
ception to this arrangement was shown 
in Fig. 3 where these controls were placed 
on the film-feed assembly in order to con- 
serve rack space for a particular in- 
stallation. In general, the separate 
panel allows the use of larger film reels 
and gives several operating as well as 
manufacturing conveniences. In the 
latter respect, the associated film-drive 
mechanism may use any of the industry 
standard motors including the combi- 
nation synchronous/interlock type. The 



use of a separate control panel therefore 
permits a variety of electrical combi- 
nations to suit the associated motor sys- 
tems without alteration of the other elec- 
trical circuits. Figure 1 shows the 
master switch designated for operation of 
a combination synchronous/interlock 
film-drive mechanism motor. This 
switch is divided into eight positions in 
order to give independent switching for 
the respective sections of the motor. It 
is also seen that on either side of the OFF 
position for synchronous motor control, 
there appears a READY position which 
permits energizing the feed and take-up 
motors before completing the circuit to 
the film-drive mechanism motor. Thus, 
the torque motors, being pre-energized 
ahead of the actual rolling of the overall 
mechanism, remove all slack in the film 
path and permit the feed and take-up 
reels to follow the acceleration or de- 
celeration of the film-drive mechanism 
motor. READY positions for interlock 
operation are not required since the 
torque motors are energized on the 
LOCKING cycle of the interlock motor 
system. 



324 



October 1952 Journal of the SMPTE Vol. 59 



DRUM 




ROLLER 



SPROCKET 



ROLLER i 



OIL DASH POT 



DRUM 



Fig. 7. Schematic of film-drive mechanism mechanical filter assembly. 



A key switch, which controls the re- 
spective torque motors through relays, 
allows film to be rewound from reel to 
reel with the direction established by the 
position of the key. For instance, if re- 
winding is to be from the lower to the 
upper reel, positioning the rewind key 
switch in the UP position connects the 
upper motor for maximum torque and 
likewise connects the lower motor for re- 
duced and reversed torque in order to 
establish tension in the film. Rewinding 
in the reverse position follows a similar 
procedure. 

C. Film-Drive Mechanism. This assem- 
bly might well be considered a basic item 
in the building-block plan for a magnetic 
recorder and/or reproducer unit. The 
foregoing discussion is therefore primarily 
concerned with the accessory items re- 
quired by the film-drive mechanism but 
varied to suit a particular installation. 
Figure 6 shows the components of the 
drive unit. The base of this assembly 
consists of a cast aluminum alloy plate 



occupying 1 0^ in. of vertical rack space. 
Attached to this plate are a drive motor, a 
mechanical filter system, magnetic 
heads either single- or triple-type a 
footage counter and several film-guide 
rollers, etc. The drive motor is worthy 
of mention to the extent that an integral 
part of it is a reduction-gear unit whose 
output shaft is suitable for direct coupling 
to the film-drive sprocket. The speed re- 
duction from motor to sprocket is ob- 
tained by single-series helical gearing. 
Ratios varying between 10 '1 and 125^9 
to suit the many permissible different 
types of motors and film speeds are used. 
Since the drive motor does not power the 
take-up system, its frame size has been 
reduced to a minimum while maintain- 
ing a power output in the order of 3 ; 1 
over that of the actual torque require- 
ment. This motor unit develops ap- 
proximately 20 mechanical watts when 
designed as a three-phase motor and 
somewhat more when designed as an 
interlock-type motor. The use of per- 
manently lubricated bearings together 



Singer and Pettus: Magnetic Recording Equipment 



325 




Fig. 8A. Single-track magnetic-head 
assembly. 

with a grease-filled gearbox reduces 
maintenance and operating attention to a 
minimum. 

The mechanical filter system, sche- 
matically shown in Fig. 7, consists of two 
drum-shaft assemblies having identical 
flywheels as inertia elements. Both 
drums are film-pulled. Two sprung 
tensioning rollers with damping applied 
to one tension roller comprise the other 
elements of the filter system, the damping 
being obtained by means of a fluid sili- 
cone oil type dashpot connected to one 
roller arm by a mechanical linkage. 
The entire system is near critically 
damped with a resonant frequency of ap- 
proximately H cycles/sec. 

Magnetic head assemblies may be, as 
previously mentioned, selected to suit 
the particular requirements of the in- 
stallation, i.e., single- or triple-type 
tracks. Either assembly is interchange- 
able with respect to the film-drive unit. 
The single-track type is shown in Fig. 
8A. Here it is seen that the head is 
mounted by means of a one-piece holder 
having a ball-and-socket type of anchor- 
age which allows longitudinal, lateral and 
transverse adjustments of the head with 
respect to the recording medium. 3 The 
use of a shoe which contacts the film on 
the edge opposite the sound track, and 
which is of a width equal to the magnetic 
track, has been found advantageous. 
This shoe maintains the plane of the film 
across the magnetic head as well as dis- 



Fig. 8B. Triple-track magnetic-head 
assembly. 

tributing the unit area pressure to mini- 
mize head wear. An interesting note is 
that the use of a hardened stainless steel 
shoe was found most practical for obtain- 
ing a wear characteristic nearly equal to 
that of the mu-metal used in the mag- 
netic-head, laminated pole pieces. 

Also seen in Fig. 8B, the triple-track 
assembly employs three heads arranged 
in line and positioned in accordance with 
the Motion Picture Research Council's 
proposed standards for sound-track posi- 
tions. 1 This assembly, while obviously 
more complex than that of the single- 
track magnetic-head unit, provides the 
same individual head adjustments al- 
though accomplished in a somewhat dif- 
ferent manner. The lateral or azimuth 
adjustment of each head is obtained by 
pivoting the head-mounting yoke on a 
supporting arm. The transverse adjust- 
ment is obtained by pivoting the indivi- 
dual arms on a lateral supporting shaft, 
and the longitudinal adjustment is ob- 
tained by moving the entire head assem- 
bly with respect to the mounting base. 3 
No supporting shoe is required by the 
triple-track assembly since the heads 
themselves contact the film uniformly 
across its width. The construction of the 
magnetic head proper, used in both 
single- and triple-track units, follows that 
described by Rettinger. 4 

When the film-drive mechanism is to 
serve as a recorder with monitoring, two 
identical head assemblies are employed, 



326 



October 1952 Journal of the SMPTE Vol. 59 



each assembly being positioned near the 
respective drum-shaft assemblies. These 
positions were chosen after extensive in- 
vestigation for optimum performance in 
both constancy of motion and uniform 
output from the recording medium. A 
more comprehensive discussion of this 
investigation was presented before the 
Society in a paper entitled "Twin-Drum 
Film-Drive Filter System for Magnetic 
Recorder-Reproducer. ' ' 5 

Among other features of the film-drive 
mechanism believed to be of interest, is 
one commonly called the free-wheeling 
sprocket. Specifically it is a means of 
disengaging the film sprocket from its 
drive source and is considered essential 
to any reproducer using an interlock mo- 
tor system. With this facility, synchro- 
nization marks may be readily brought 
to a reference position without disturbing 
the interlock of the driving motor. Such 
an assembly is shown in Fig. 9 in an ex- 
panded view. Essentially, this consists 
of a multi-jaw coupling which may be 
manually disengaged to free the film 
sprocket. It will be seen that one-half of 
the multi-jaw coupling is fixed to the 
sprocket drive shaft and following this is 
a spinner knob which contains the mating 
half of the multi-jaw coupling, free to ro- 
tate on the shaft. On the rear side of 
the spinner knob is a driving pin which 
accurately engages at all times with a 
hole in the film sprocket proper and 
therefore serves to drive the latter. 
Between the spinner knob and the 
sprocket lies a compression spring which 
normally forces the spinner knob toward 
the fixed half of the multi-jaw coupling. 
By exerting an inward force on the spin- 
ner knob, the coupling becomes dis- 
engaged and the film sprocket is then 
"free-wheeled." Following the sprocket 
is a collar which is likewise driven by a 
pin engaging the film sprocket and ro- 
tates at all times with the sprocket. On 
the rear face of this collar is a ladder- 
chain sprocket which drives the footage 
counter in synchronism. Behind this is 
a smaller collar fixed to the drive shaft 




Fig. 9. Free-wheeling sprocket and drive- 
motor assembly. 



which forms an axial stop for the 
entire assembly when the foregoing items 
are assembled in their true position on 
the drive shaft. Since the film sprocket 
contains 32 teeth in the case of 35mm 
applications, a multi-jaw coupling also 
having 32 teeth was chosen. It follows 
therefore that synchronism is maintained 
within one sprocket pitch for 35mm film 
and to an even closer degree for 16mm 
film where the sprocket contains 20 
teeth. This arrangement will advance 
or retract film through the driving mech- 
anism at the rate of approximately 6 in. 
per revolution of the spinner knob. 

D. Accessory Equipment. In the build- 
ing-block plan, a number of accessories 
have been developed to provide addi- 
tional conveniences in operation as well 
as a means of reducing production costs. 
These include: (a) magnetic erasing fa- 
cilities while recording either single or 
triple tracks; (b) a predetermining re- 
wind footage counter; and (c) photo- 
graphic-type sound reproducers for both 
16mm and 35mm films. The erasing 
unit employs two erase heads in cascade 
for each sound track, making a total of 
six heads in the unit. The geometry of 
the film path between feed reel and film- 
drive mechanism is slightly modified to 
bring the erase unit into use. This con- 
sists of threading the film about a series of 



Singer and Pettus: Magnetic Recording Equipment 



327 





Fig. 10. Predetermining counter assembly. 




Fig. 11. 35mm photographic reproducer assembly. 




328 



Fig. 12. Oscillator-preamplifier. 
October 1952 Journal of the SMPTE Vol. 59 



fixed rollers which allow the film to con- 
tact the erase heads. When erasing is 
not wanted, the film is threaded directly 
past the erasing unit. Thus, the differ- 
ence in film threading, plus an enclosure 
around the erasing heads, reduces the 
accidental use of the erasing facilities to a 
minimum. Each erase head dissipates 
1.6 w, making a total of 3.2 w per track 
of erase current power. The frequency 
is nominally 68 kc and derived from the 
recording bias oscillator. This amount 
of erase power provides a 70-db erasure 
below 100% modulation or results equiva- 
lent to that obtained by the conven- 
tional 60-cycle bulk eraser. 

The predetermining footage counter 
accessory is shown in Fig. 10. It is used 
in rewinding to a given point without 
operator attention. A specific use for 
this convenience is, for example, in scor- 
ing music, where playbacks and transfers 
are involved. This assembly consists of 
a special counter which is film-driven and 
several additional relays in the electrical 
circuit for controlling the film feed and 
take-up torque motors. In operation, 
the counter is set to a given number of 
feet to be rewound and the rewind con- 
trol switch positioned in the desired di- 
rection of rewinding. As the film travels 
from reel to reel, the counter subtracts 
toward zero. At 10 ft from zero the 
counter anticipates and trips an electrical 
control which applies a braking voltage 
to the respective torque motors. This 
braking action is maintained by a time- 
delay relay circuit during the deceler- 
ation period, and when the counter 
reaches zero both the braking action as 
well as the power are released. At this 
point, the torque motors are automati- 
cally restored to their normal functions 
of feed and take-up. The footage coun- 
ter is driven by wrapping the film about 
a large rubber-tired roller, with the de- 
gree of wrap being maintained by two 
smaller rollers of the conventional type. 
When the predetermining counter oper- 
ation is not wanted, the film path for re- 
winding is threaded to by-pass the coun- 



ter drive. The electrical control ele- 
ments have been designed to stop film 
travel within two to three feet of a given 
point, this point being in the direction of 
over-travel. The starting point is then 
brought into view during rethreading of 
the film-drive mechanism, since the oper- 
ator's natural tendency is to pull this 
amount of slack film from the feed reel for 
the threading operation. Exact syn- 
chronism is then obtained by turning the 
free-wheeling sprocket. 

The third accessory item is a photo- 
graphic sound reproducer unit for both 
1 6mm and 35mm applications. The latter, 
shown in Fig. 11, is suitable for 100- 
mil standard, 100-mil push-pull and 200- 
mil push-pull sound tracks. It is be- 
lieved that most sound-recording plants 
find it necessary to handle photographic 
records at different times regardless of 
the extent of their magnetic plant fa- 
cilities. Since many of the components 
of a magnetic reproducing channel might 
well be common to a photographic repro- 
ducing channel, it is logical that a dual- 
purpose reproducer will reduce the over- 
all plant investment. Again the build- 
ing-block plan permits the use of another 
unit in conjunction with those items con- 
sidered common to either type of repro- 
ducer. The photographic sound repro- 
ducer need have only the necessary opti- 
cal-scanning facilities and a means of 
directing the film for scanning. This has 
been accomplished by mounting the 
necessary optical elements on a panel 8|- 
in. high and assembling in the standard 
relay rack directly below the magnetic 
film-drive mechanism. The photo- 
graphic reproducer contains its own 
mechanical filter system but its driving 
power is derived from a synchronous rub- 
ber-belt drive from the magnetic film- 
drive unit. In operation, the film is 
threaded to by-pass the magnetic unit. 
Likewise, the photographic unit is by- 
passed when using the magnetic unit. 
Preamplifiers for both the 16mm and 
35mm reproducers are mounted directly 
behind the respective mechanisms and 



Singer and Pettus: Magnetic Recording Equipment 



329 




Fig. 13. Erase amplifier (front view). 




330 



Fig. 14. Erase amplifier (service position). 
October 1952 Journal of the SMPTE Vol. 59 



provide an output level of approximately 
2 dbm and 12 dbm, respectively. 

A variety of amplifiers and bias oscil- 
lators are available to complement the 
above-mentioned alternative equipment 
arrangements. For single-track record- 
ing and reproducing, the amplifier- 
oscillator known as MI-10248 or MI- 
10248-A, shown in Fig. 12, is provided. 
This unit contains a combining network, 
bias oscillator and bias meter. In addi- 
tion, it also provides for a separate self- 
contained playback amplifier capable of 
amplifying the signal from the monitor 
head to a level of +4 dbm. Output im- 
pedances of 10, 250 and 600 ohms are 
available so as to provide for headset 
monitor or for transmission to the re- 
recording channel. Suitable switching 
facilities deactivate the oscillator during 
playback or in the OFF position. The 
oscillator also contains a high-frequency 
boost equalizer which is used to shape the 
recording characteristic to obtain flat 
output to 8000 cycles. A separate wind- 
ing on the oscillator coil permits connec- 
tion to an MI-10263 Erase Amplifier as 
shown in Figs. 13 and 14. By means of 
this amplifier, it is possible to raise the 
output voltage from the oscillator to a 
level sufficient for erasing. This erase 
amplifier contains its own a-c power sup- 
ply and is capable of delivering 50 w at 
68 kc at a distortion of less than 0.5%. 
At normal erase power requirements, the 
wave-form distortion from this amplifier 
is on the order of 0.1% or less. 

For triple-track recording or repro- 
ducing, a three-channel bias oscillator is 
provided. This oscillator, known as the 
MI-10228-A, is usually mounted to- 
gether with the MI-10262-A Switching 
Panel on a common frame and is shown 
in Figs. 15 and 16. A master oscillator 
operating at a nominal frequency of 68 
kc supplies three independent push-pull 
amplifiers which in turn furnish bias cur- 
rent to the three recording heads. The 
switching panel permits the combining of 
the bias currents with the signal before it 
reaches the heads and also provides 



switching means for turning the MI- 
10228-A oscillator on and off. Three 
separate bias meters are contained on the 
switching panel to permit independent 
metering of the three recording heads. 
For playback, there are available plug-in 
amplifiers (Fig. 17) which may be con- 
nected singly or in cascade so as to obtain 
almost any desired output level from the 
reproducing heads with frequency char- 
acteristics flat up to 8000 cycles. Six 
such playback amplifiers are housed on a 
common shelf. These six amplifiers fur- 
nish the playback amplification for a 
triple-track reproducing setup. For re- 
. cording amplifiers, plug-in amplifiers, in 
external appearance very similar to the 
playback amplifiers, are available. 
However, any power amplifier capable 
of providing a level of +22 dbm at an 
output impedance of 600 ohms, may be 
used. In order to obtain the optimum 
signal-to-noise ratio, we have standard- 
ized on the use of a low-frequency pre- 
equalizer during recording. This unit, 
shown in Fig. 18, raises the 60-cycle re- 
gion of the recording characteristic by 6 
db and consequently permits the use of 6 
db less post-equalization during repro- 
ducing. This expedient reflects in a 
gain in signal-to-noise ratio, since hum 
frequencies, such as 60 cycles, now re- 
quire 6 db less playback amplification. 
The insertion loss of this constant resist- 
ance equalizer is 10 db. It may be con- 
nected before or after the power amplifier 
dependent on the power-handling capac- 
ity of this amplifier. The performance 
of these magnetic channels is best ex- 
pressed by stating that the overall fre- 
quency response is flat within 1 db from 
40 to 8000 cycles at film speeds of 90 or 
45 fpm, and flat within 1 db from 50 to 
7000 cycles at film speed of 36 fpm. The 
signal-to-noise ratio is consistently 60 db 
or better, referred to 100% modulated 
track. In order to obtain this perform- 
ance, all heaters are operated from d-c 
supplies which have a ripple content of 
6 mv or less. The ripple content of the 
B supplies is 1 mv or less. The flutter 



Singer and Pettus: Magnetic Recording Equipment 



331 





Fig. 15. Triple-track oscillator and switching panel 




Fig. 16. Triple-track oscillator and switching panel (cover removed). 



332 



October 1952 Journal of the SMPTE Vol. 59 




Fig. 17. Magnetic playback amplifier. 




Fig. 18. Recording equalizer. 

content of a recording reproduced on 
either single- or triple-track equipments is 
less than 0.1% rms total with less than 
0.05% rms being 96 cycles flutter. 5 Re- 
winding speed is approximately 900 fpm. 
Starting time is in the order of 4 sec for 
35mm or 17^mm equipment at 90 fpm, 
and approximately 5 sec for 1 6mm equip- 
ment at 36 fpm. 

In order to complement the photo- 
graphic-film reproducing facilities the 
following amplifiers are available: 




Fig. 19. 16mm photocell amplifier. 

1. For 16mm reproducing, the MI- 
10239-A, shown in Fig. 19, can be sup- 
plied. This is a two-stage negative feed- 
back amplifier capable of furnishing 
photocell polarizing potential and of 
amplifying the output from a photocell to 
a level of 10 dbm. 

2. For the reproducing of 35mm opti- 
cal track there is available an amplifier of 
the plug-in broadcast type known as 
MI-10271 which in appearance is similar 
to magnetic playback amplifiers. This 






Singer and Pettus: Magnetic Recording Equipment 



333 



amplifier also furnishes photocell polariz- 
ing potential and is customarily used 
with a balancing network which forms 
part of the MI-29135 optical system. 

References 

1. Motion Picture Research Council Rec- 
ommendation 58. 301 -B. 

2. Kurt Singer and H. Gonnell Ward, "A 
technical solution of magnetic recording 
cost reduction," Jour. SMPTE, 58: 329- 
340, Apr. 1952. 

3. Terms are those defined by N. M. 
Haynes, "Magnetic tape and head align- 



ment nomenclature," Audio Eng., 33: 
22, June 1949. 

4. M. Rettinger, "A magnetic record- 
reproduce head," Jour. SMPTE, 55: 
377-390, Oct. 1950. 

5. Carl E. Hittle, "Twin-drum film-drive 
filter system for magnetic recorder- 
reproducer," Jour. SMPTE, 58: 323- 
328, Apr. 1952. 

6. Proposed American Standard, Z57.1 /68, 
Method for Determining Flutter Con- 
tent of Sound Recorders and Repro- 
ducers, American Standards Assn., 70 
E. 45 St., New York City. 



334 



October 1952 Journal of the SMPTE Vol. 59 



A-C High- Intensity Arc Slide Projector 

By ARTHUR J. HATCH 

This paper describes a high-intensity arc slide projector which is powered 
from a 110-v, 60-cycle convenience outlet and requires only 10-amp supply. 
The resulting intensity of illumination is sufficient for screens of 35 ft in width. 



A 



modern slide projector, shown in 
Fig. 1, using a high-intensity a-c carbon 
arc as a light source, has been developed 
to cover both the large-screen areas of 
drive-in theaters and smaller screens 
where an exceptionally high level of 
illumination is desired. 

With this high-intensity a-c arc 
adapted for 3| in. by 4 in. slides, 7500 
Im are projected, with no slide in the 
carrier. Expressed a different way, this 
7500 1m projected to a 35-ft wide screen 
will produce a screen brightness of 
approximately 9 ft-L, which incidentally 
is the lower limit of the SMPTE screen 
brightness range for 35mm projection. 
For a 50-ft wide picture the screen 
brightness will be nearly equal to that 
usually obtained on the average 50-ft 
drive-in screen with 35mm projection. 

With small-size screens of 10 to 12 ft 
in width, the brightness may approxi- 
mate 70 ft-L, which is sufficient to obtain 
a reasonably good contrast even with the 
normal room lighting remaining on. 

The complete projector comprises the 
arc lamphouse, optical system, slide 
carriers, and fan and transformer, all 
assembled as a table unit 78 in. long 
and weighing 175 Ib. The table is ad- 
justable in height by means of its four 

Presented on April 22, 1952, at the Society's 
Convention at Chicago, 111., by Arthur 
J. Hatch, The Strong Electric Corp., 
87 City Park Ave., Toledo 2, Ohio. 



legs, from 36 in. to 56 in., and tillable 
from 10 upward to 30 downward. 

The reflector-type arc lamphouse and 
power supply elements are essentially 
the same units used in the "Trouper" 
arc spotlight.* The lamphouse is com- 
plete with carbon holders, motor-driven 
carbon feed, reflector tilt adjustments, 
arc focus knob and arc imager screen. 

The trim of 6 mm by 7 in. copper- 
coated high-intensity a-c carbons is 
burned in coaxial alignment at 45 amp 
and 21 v a-c. The burning time for a 
single trim of carbons is 1 hr 20 min. 

Although the first development with 
this new a-c projector has been for 
3j by 4 in. slides, simple adaptations 
can be used to project both larger and 
smaller material. However, in the case 
of 2 in. by 2 in. material or smaller, 
heat-removing means in the form of heat 
filters or heat deflectors will have to be 
used in the light beam to prevent 
damage to the slide. 

The optical system is arranged so 
that the light from the arc is gathered 
by a lOj-in. diameter elliptical reflector 
which has a focus of 3 J in. and a working 
distance of 24 in. This reflector con- 
verges the beam of light through a 
plano-convex lens and thence through 
the slide aperture to the objective lens. 



* R. Ayling "New portable high-intensity 
arc spotlight," Jour. SMPE, 53: 408-416, 
Oct. 1949. 



October 1952 Journal of the SMPTE Vol.59 



335 




Fig. 1. A-C Arc Slide Projector. 



The magnification of the carbon crater 
on the slide aperture is sufficient to 
cover a 2 in. by 2 in. slide. When 
3j in. by 4 in. slides are projected, a 
negative lens is placed in the beam of 
light between the lamp and plano- 
convex lens to increase the magnification 
sufficiently to cover the larger aperture. 
The power transformer which isolates 
the a-c line potential from the lamp- 
house draws 10 amp from any 115-v 
convenience outlet and delivers 45 amp 
at 21 v to the arc. The eight-point 
rotary tap switch and indicating meter 



provide a convenient means of coi 
pensating for commercial variations 
the a-c line voltage. 

The indicating meter, in reality a volt- 
meter with a suppressed zero, is con- 
nected across a portion of the trans- 
former primary winding. When the 
hand of the indicating meter scales in 
the green zone, the volts per turn of the 
transformer primary are at the right 
value to deliver the correct amount of 
power to the arc. The tap switch is 
simply turned until the primary volts 



336 



October 1952 Journal of the SMPTE Vol.59 



per turn are correct as indicated by the 
meter. 

A fan of 50 cu ft/min capacity directs 
a moving air stream across the slide to 
prevent damage to the slide. This fan 
is started when the arc power supply is 
turned on. With the cooling from this 
blower, it is possible to project dense 
3j in. by 4 in. slides for periods of an 
hour or more continuously without 
visible deterioration to the slide. 

The arc "on-off" switch is located at 
the top rear of the lamphouse. A 
manually operated dowser interposed 
just before the slide carrier and lens 
assembly enables the arc to be burned 
in a stand-by condition. 

Single-element objective lenses have 
been found suitable for use with 3j in. 
by 4 in. slides in the focal length range 



of 17 in. to 30 in. Corrected objective 
systems are generally necessary for focal 
lengths shorter than 17 in. 

Discussion 

J. A. Tanney (S.O.S. Cinema Supply 
Corp.} : Have you had any experience 
with wide-angle lenses of comparatively 
short throw? 

Mr. Hatch: I understand that there is 
a type of lens which has recently appeared 
which will give a wide-angle picture with 
a very short throw. It is possible that 
such an objective system could be coupled 
with this projector. 

Mr. Tanney: What I had in mind was 
its possible ues in TV studios for back- 
grounds or in motion picture work for 
still backgrounds. 

Mr. Hatch: We are going to investigate 
those possibilities in connection with this 
projector. 



Arthur J. Hatch: Arc Slide Projector 



337 



Proposed American Standard 



PH22.90 Aperture Calibration of Motion Picture Lenses 



STARTING ABOUT 1940, there has been a 
rapidly growing need in the motion 
picture industry for a more accurate 
expression of the photographic speed of 
a lens than is afforded by the simple 
/-number ratio. The Proposed Ameri- 
can Standard appearing on the following 
pages is the product of many years' 
industrious and patient effort to achieve 
agreement on a standard photometric 
method of aperture calibration. It is 
published here for 6-month trial and 
criticism. All comments should be 
sent to Henry Kogel, SMPTE Staff 
Engineer, prior to April 15, 1953, along 
with a carbon for R. Kingslake, Chair- 
man of the Optics Committee. 

The problem is essentially this: the 
density of a photographic image depends 
on (a) the brightness of the subject, 
(b) the effective speed of the lens, (c) 
the speed of the film, (d) the exposure 
time, and (e) processing of the film. 
In modern motion picture production 
all these factors except (b) are con- 
trolled or known to within a few per 
cent, but the supposed speed of the lens 
may be in error by as much as 60 or 
70%. This is caused by loss of light 
through surface reflections or direct 
absorption in the lens, and occasionally 
to incorrect marking of the /-number 
scale. 

By August 1947, no less than eight 
papers on lens calibration had appeared 
in this JOURNAL. 

The Standards Committee, therefore, 
formed a Subcommittee on Lens Cali- 
bration to study the whole subject and 
to recommend a standard procedure 
for measuring the effective photographic 
speed of a lens. In October 1949 the 
Subcommittee published a report of 



their investigations and recommenda- 
tions, which became the basis of the 
present proposal. The introduction to 
the report stated in part: "The demand 
for a photometric type of aperture 
calibration ("T-stop") is becoming 
increasingly felt, and it has the ad- 
vantage that diaphragms of any shape, 
pentagonal, scalloped or irregular, can 
be correctly labeled with as much ease 
as a circular one. The presence or 
absence of antireflection coatings is 
automatically accounted for in the 
calibration, and so also are factory 
variations in the focal length and in the 
iris mechanism. Illumination on the 
film in the center of the field will there- 
fore be the same for all lenses at the same 
T-stop, assuming that the object is a 
uniform plane surface perpendicular to 
the lens axis. It is implicit, also, that 
each lens shall be individually calibrated 
if the photometric method is used." 

In November 1949 the Subcommittee 
was given formal status of its own in the 
creation of the Optics Committee under 
the chairmanship of Mr. Kingslake. 
This Committee achieved agreement on 
the final version of the proposal at its 
May 3, 1951, meeting and forwarded it 
to the Standards Committee for proc- 
essing as an American Standard. The 
ballot of the Standards Committee on 
the question of preliminary publication 
brought forth several negative votes, all 
of which were based on objections to 
paragraphs dealing with some of the 
practical applications of T-stops. These 
were not fundamental aspects of the 
proposal and have therefore been 
eliminated, paving the way for its 
present publication. 



338 



October 1952 Journal of the SMPTE Vol. 59 



Proposed American Standard 

Aperture Calibration 
of Motion Picture Lenses 



PH22.90 



p. 1 of 10 pp. 



1. Scope 

1.1 The purpose of this standard is to define 
the f and T numbers used to express the rela- 
tive aperture of a photographic objective. A 
second purpose is to establish means for cali- 
brating the diaphragms of objectives in both 
the f and T systems, with suitable tolerance 
specifications. 

1.2 The f number of a lens represents a true 
geometrical measure of the relative aperture. 

1.3 The T number is a photometrically deter- 
mined measure of the relative aperture of a 
lens adjusted to take proper account of the 
lens transmittance, so that the illuminance in 
the center of the lens field will be the same for 
all lenses at the same T-stop setting. This as- 
sumes that the object is a uniform plane diffus- 
ing surface perpendicular to the lens axis. 

1.4 It should perhaps be mentioned that the 
photometric calibration of a lens diaphragm 
as contemplated by the T system of diaphragm 
marking established by this specification is 
only one step in extending the control for the 
purpose of producing negatives of a desired 
uniform density. The density of a negative is 
dependent upon the illumination and reflect- 
ance of the object photographed, the correct- 
ness of the diaphragm marking, the absorp- 
tion of the lens, the accuracy of timing of the 
exposure, the uniformity of the emulsion em- 
ployed, and complete control of the proces- 
sing. The application of the T-stop system is 
designed to improve the control as regards 
correctness of diaphragm marking and ab- 
sorption of the lens. The importance and need 
for this particular control increases as the con- 
trol of the other factors enumerated is im- 
proved. 

2. Theory 

The illuminance at the center of the 



image of a uniform plane extended object 
perpendicular to and centered on the lens 
axis, when the lens has a circular aperture, is 
given by 



E = TT t B sin 2 



(1) 



2.2 In this formula: E is the illuminance in 
lumens per unit of area; t is the lens transmit- 
tance, expressed as the ratio of emerging flux 
to entering flux for a beam sufficiently narrow 
to pass through the lens without obstruction 
by the lens mount; B is the object luminance 
in candles per square unit; and 6 is the semi- 
angle of the cone subtended by the circular 
exit pupil of the lens at the point where the 
lens axis intersects the image plane. 

2.3 If the lens can be assumed to be apla- 
natic, that is, to be free from spherical aberra- 
tion and to satisfy the sine condition, and if 
the object is very distant, then the value of sin 
will be given by 



sin = 



(2) 



where Y is the semidiameter of the circular 
entrance pupil of the lens and f is the focal 
length. The validity of this equation may be 
seen by reference to Fig. 1, remembering that 
in a lens having the type of correction assumed 
in this paragraph, the principal planes of 
Gauss are in reality portions of spheres cen- 
tered about the axial object and image points, 
respectively. 

2.4 If the lens aperture is not circular, which 
will often occur when the iris is partly closed, 
the angle B has no meaning. In such a case, 
we may define the effective, diameter, D', of 
the entrance pupil in terms of its area, A, by 

A = * P' 2 (3) 

4 



APPROVED 



October 1952 Journal of the SMPTE Vol. 59 



339 



Proposed American Standard 

Aperture Calibration 
of Motion Picture Lenses 



PH22.90 



p. 2 of 10 pp. 




whence 



2 



(4) 



2.5 For an aplanatic lens, we may now re- 
place sin 6 by D'/2f, and the image illumi- 
nance equation (1) becomes 

E - TT t B (D'/20 2 
whence by equation (4), we find 

E = t BA/f 2 (5) 

3. Definition of t Number 

3.1 For a lens of the type assumed, having a 
circular aperture, which is perfectly corrected 
for spherical aberration and satisfies the sine 
condition, and which is also assumed to form 
an image in air of a very distant object, the f 
number of the lens is defined by the equation 

f number =-L= - 

D 2 sin (6) 

where is the semiangle of the cone subtended 
by the circular exit pupil of the lens at the 
point where the lens axis intersects the plane 
of the image of the assumed distant object, 
and the entrance pupil has a diameter D. 

3.2 If the entrance pupil is not circular, this 
relation becomes 



/number = / u\ 

D' 2V A (7) 

following the reasoning of Section 2.4. 

3.3 If the aperture is circular, but the lens 
does not satisfy the sine condition, then f/D 
will not be equal to l/(2sin$). In such a case, 
the f number of the lens is to be defined by 
l/(2 sin B) rather than by the ratio f/D. This 
value is chosen because both the image illumi- 
nance and the depth of field of the lens de- 
pend directly on sin 0. In such a lens, then, the 
marked f number will not be equal to the sim- 
ple ratio of the focal length to the diameter of 
the entrance pupil. 

3.4 The procedure for measuring the f num- 
ber of a lens with a distant object is given in 
Section 11. 

3.5 In terms of f number, equation (1) giving 
the image illuminance becomes 



E - TT t B/4(f number) 2 



(8) 



4. Effective and Equivalent f Number 
of a Lens Used at Finite Magnification 

4.1 If a lens with a circular aperture is used 
to form an image at a finite magnification m, 
the image illuminance will, as always, be 
given by equation (1). 



NOT APPROVED 



340 



October 1952 Journal of the SMPTE Vol. 59 



Proposed American Standard 

Aperture Calibration 
of Motion Picture Lenses 



PH22.90 



4.2 The Effective f number of the lens, which 
is to be used to determine the image illumi- 
nance by equation (8), is then defined by 

Effective f number = /o\ 

2 sin 8 V' 

where # m changes as the magnification m in- 
creases. 

4.3 For an infinitely thin lens, or for a thick 
lens in which the entrance and exit pupils coin- 
cide with the first and second principal planes, 
respectively, and in which the light beam is 
limited only by the iris diaphragm, the Effec- 
tive f number will be related to the f number by 

(Effective f number for magnification m) 

(f number) (1 + m) (10) 

4.4 However, many lenses cannot be re- 
garded as being "thin," and in such cases the 
Effective f number at a finite magnification 
will not* be equal to the infinity f number 
multiplied by (1 + m). However, the photog- 
rapher knows from long experience that he 
should always multiply the marked f number 
of a lens by (1 -f m) in order to determine the 
Effective f number at a finite magnification m. 
Therefore, in order that this procedure can 
continue to be used, it is suggested that if a 
lens is designed to work at or near some par- 
ticular finite magnification m, the aperture 
markings should be engraved with 'the "Equiv- 
alent f number" defined by 

* For example, an afocal lens of symmetrical con- 
struction can be used as a printer or copying lens at 
unit magnification. The Effective f number is then 
equal to the f number of the half system, but since the 
focal length of the whole lens is infinite, no meaning 
can be given to the / number of the whole system. For 
other examples see: R. Kingslake, "The effective aper- 
ture of a photographic objective," J. Optical Soc. 
Am., vol. 35, pp. 518-520 (1945). 



p. 3 of 10 pp. 



Equivalent f number == 

[Effective f number at magnification m~I ^ ' 
L 1 +m J 

5. Definition of T Number 

5.1 When lenses are marked in accordance 
with the f system, differences of value in the 
factor t of equation (1 ) are completely ignored, 
with the consequence that for a given f -setting 
of the diaphragms, even though correctly 
marked, the exposures made with different 
lenses may vary greatly, this variation arising 
from a variation in the number of component 
elements of the different lenses and from the 
large differences in the values of transmittance 
that exist between coated and uncoated lenses. 
The T system defined in this section is a new 
system of diaphragm graduation designed to 
compensate for this variation. With the T sys- 
tem of graduation the image illuminance in 
the center of the field is independent of the 
variations in lens structure enumerated above. 

5.2 For a lens used with a distant object, the 
T number is defined as the f number of an 
ideal lens having TOO per cent transmittance 
and a circular aperture, which would give the 
same central-image illuminance as the actual 
lens at the specified stop opening. 

5.3 Hence, for a lens with a circular aper- 
ture, following the argument of equation (8), 

T number = f number 

VT 



(12) 



and for a lens with an entrance pupil of any 
shape and area A, the corresponding formula 
is 

T number 

tA 



71 03) 



5.4 In practice, however, it is expected that 
the normal procedure will be to re-engrave 
the diaphragm ring on the lens at a series of 



NOT APPROVED 



October 1952 Journal of the SMPTE Vol. 59 



341 



Proposed American Standard 

Aperture Calibration 
of Motion Picture Lenses 



PH22.90 



p. 4 of 10 pp. 



definite T numbers, rather than to measure the 
T number corresponding to each of the exist- 
ing marked f numbers. 

5.5 It may be remarked again that the T 
number is a photometrically determined quan- 
tity, whereas the f number is a geometrical 
quantity. Since the T numbers are determined 
photometrically, they automatically take ac- 
count of the size and shape of the aperture, 
the actual focal length of the lens, the lens 
transmittance, and any internally reflected 
stray light which may happen to strike the 
film at the center of the field (such as in a flare 
spot). It is implicit in the T number system of 
aperture markings that every lens should be 
individually calibrated. 

5.6 For a lens designed to be used at finite 
magnification, the engraved T number will 
correspond to the Equivalent f number defined 
by equation (1 1). 

5.7 The procedure for measuring the T num- 
ber of a lens is given in Section 13. 

6. Standard Series of Aperture 
Markings 

6.1 The diaphragm ring of a lens shall be 
marked at every whole stop on either system. 
A "whole stop" is taken to represent an inter- 
val of double or half the image illuminance, 
corresponding to a ratio of \/2 or \ f 0.5 in the 
diameter of a circular lens aperture. By con- 
vention, the series of whole stop numbers to 
be used are accurately: 

0.71, 1.00, 1.41, 2.00, 2.83, 4.00, 
5.66, 8.00, 1 1.3, 16.0, 22.6, 32.0 

6.2 These marks shall be engraved on the 
lens as follows: 0.7, 1 , 1 .4, 2, 2.8, 4, 5.6, 8, 1 1 , 
16, 22, 32. The maximum aperture of the lens 



shall be marked with its measured f number or 
T number, stated to one decimal place. These 
recommendations follow American Standard 
Z38.4.7-1943. 

6.3 In setting the lens aperture, it is assumed 
that the diaphragm ring will always be turned 
in the closing direction, and not in the opening 
direction; this is to eliminate backlash effects. 

7. Subdivision of a Whole Stop 

7.1 If it is desired *o subdivide a "whole 
stop" interval, we may refer to a fraction S of 
a stop, defined so as to yield a ratio of image 
illuminance R equal to 2 s or (0.5) s . Then, for 
any given illuminance-ratio R, the correspond- 
ing fraction of a stop will be given by S (log 
R)/(log 2) = 3.32 log R. A few typical ex- 
amples are given in the following table: 

Fraction of a Stop (S) Illuminance Ratio (R) 



one-tenth 

one-sixth 

one-quarter 

one-third 

one-half 

two-thirds 

three-quarters 

a whole stop 



.072 or 0.932 

.122 or 0.891 

.189 or 0.841 

.260 or 0.793 

.414 or 0.707 

1.587 or 0.630 

1.682 or 0.594 

2.0 or 0.5 



7.2 When engraving a lens, each whole stop 
interval may be divided into three subdivisions 
by dots or marks (not numbered), the dots 
being at "thirds of a stop," namely, 0.7, 0.8, 
0.9, LQ, 1.13, 1.27, L4, 1.6, 1.8, 2,0, 2.2, 
2.5, 2JJ, 3.2, 3.6, 4.0, 4.5, 5.0, 5^6, 6.3, 7.1, 
8.0, 9.0, 10.0, 11.3, 12.7, 14.2, 16, 18, 20, 
23, 25, 28, 32 

7.3 The reason for dividing each stop inter- 
val into three parts is so that the lens aper- 
tures will agree with the exposure-meter mark- 
ings stated in American Standard Z52.12- 
1944, page 5. The same cube-root-of-two 
series is used for the Exposure Index of a film, 



NOT APPROVED 



342 



October 1952 Journal of the SMPTE Vol. 59 



Proposed American Standard 

Aperture Calibration 
of Motion Picture Lenses 



PH22.90 



see American Standard Z38. 2. 1-1947, page 
11. One-third of a stop represents a logarith- 
mic illumination ratio equal to 0.1, which is 
the transmittance of a neutral density of 0.1. 
The ratio of successive circular stop diameters 
is equal to \/2 1.123. 

8. Symbols 

8.1 Lenses calibrated on the f system should 
bear the designation f/ or f: followed by the 
numerals (see American Standard 238.4.7- 
1943). 

8.2 Lenses calibrated on the T-stop system 
should bear the designation T or T followed 
by the numerals. 

9. Accuracy of Marking (f System) 

9.1 The maximum opening of a lens on the f 
system shall be marked with an accuracy of 

- 12 per cent of area, or 6 per cent of 
diameter.* 

9.2 NOTE: Since in most factories a blanket 
calibration is generally used for the f aper- 
tures of a complete run of lenses of the same 
type, the smaller openings may be in error by 

* Z38.4.4-1942 the engraved focal length of lenses 
for still picture photography must be within 4 per 
cent of its true value, and in Z38. 4.7-1 943 the meas- 
ured diameter of the maximum entering beam shall 
be at least 95 per cent of the quotient obtained by 
dividing the engraved focal length by the engraved f 
number. Thus by combining these tolerances we find 
that the diameter of the maximum lens aperture may 
be in error by as much as 9 .per cent. This represents 
an error in area of 18 per cent, or one-quarter of a 
stop, which is felt to be unnecessarily large for the 
maximum aperture. The proposed tolerance on aper- 
ture marking for motion picture objective lenses allows 
less latitude than that provided for still picture camera 
lenses by Sectional Committee Z38 (Photography), be- 
cause of the stricter requirements in cinematography 
on the same continuous length of film using different 
lenses. 



p. 5 of 10 pp. 



25 per cent of area, or 12 per cent of 
diameter (one-third of a stop), particularly in 
short-focus lenses. These figures are based on 
the assumption that the iris will always be 
closed down to the desired aperture and not 
opened up from a smaller aperture, to elimi- 
nate backlash effects. 

10. Accuracy of Marking (T System) 

10.1 Since each lens is individually cali- 
brated, an accuracy of one-sixth of a stop (10 
per cent in illumination or 5 per cent in diame- 
ter) becomes entirely possible throughout the 
whole range of the diaphragm scale. This is 
assuming that the diaphragm is always closed 
down to the desired aperture and not opened 
up from a smaller aperture, to eliminate back- 
lash effects. 

10.2 Alternatively, the manufacturer should 
be prepared to guarantee this accuracy even 
though each stop marking may not be individ- 
ually determined. 

10.3 It may be of interest to indicate the ap- 
proximate magnitude of this tolerance. Since 
5 per cent in diameter corresponds to 5 per 
cent in f number, a lens of aperture nominally 
f/2 may be anywhere between f/1.90 and 
f/2.10. A lens nominally f/4.5 may lie be- 
tween f/4.28 and f/4.72; and a nominal f/8 
may lie anywhere between f/7.6 and f/8. 4. 

11. Measurement of t Apertures 
(Distant Object) 

11.1 The procedure for measuring the f num- 
ber of any lens having a circular diaphragm 
aperture is described in American Standard 
Z38.4.20-1948, paragraph 3. 

11.2 If the entrance pupil is noncircular, it 
is necessary to measure its area. This may be 
done conveniently by mounting a point source 



NOT APPROVED 



October 1952 Journal of the SMPTE Vol. 59 



343 



Proposed American Standard 

Aperture Calibration 
of Motion Picture Lenses 



PH22.90 



p. 6 of 10 pp. 



of light such as a small hole in front of a lamp 
bulb, or a 2-watt zirconium lamp, at the rear 
focal point of the lens, and allowing the light 
beam which emerges from the front of the lens 
to fall upon a piece of photographic material. 
After processing, the recorded area is meas- 
ured with a planimeter and applied in equa- 
tion (7). If the lens is too small for this pro- 
cedure to be employed, it may be placed in a 
suitable telecentric projector working at a 
known magnification (a workshop profile pro- 
jector is suitable), the back of the test lens be- 
ing towards the source of light. The entrance 
pupil then will be projected onto the screen 
of the projector at a known magnification, 
whence its area can be determined with a 
planimeter. 

12. Measurement of f Apertures 
(Near Object) 

12.1 To measure the Effective / number of a 
lens when used with a near object, it is neces- 
sary to determine the angle 6 in equation (9). 
This may be done by using a point source of 
light at the correct axial object position, and 
measuring the diameter of the emerging beam 
at two widely separated planes a known dis- 
tance apart. A simple computation will enable 
the semicone-angle to be determined. 

12.2 The Effective f number is defined by 
l/(2 sin 6); and the Equivalent f number for 
engraving on the lens barrel will then be equal 
to the Effective f number divided by (1 + m), 
where m is the image magnification. (See Sec- 
tion 4.4 above.) 

13. Photometric Calibration of a Lens 

13.1.1 Since T-stops are based on a meas- 
urement of the illumination produced by the 
lens at the center of the field, it is first neces- 



sary to define the latter term. For the purpose 
of illumination or flux measurements, the term 
"center of the field" shall be taken to mean 
any area within a central circle approximately 
3 mm in diameter for 35mm or 16mm frames, 
or 1.5 mm in diameter for 8mm frames. 

13.1.2 The light used in making the deter- 
mination shall be white,* and the sensitivity 
characteristic of the photoelectric receiver 
shall approximate that of ordinary panchro- 
matic emulsion. t It is considered that these 
factors are not at all critical and no closer spe- 
cification than this is necessary. Obviously 
errors will arise if the lens has a strongly selec- 
tive transmission, but such lenses would be 
undesirable for other reasons. 

13.1.3 The incident light shall fill a circular 
field whose angular diameter is no more than 
10 degrees in excess of the diagonal of the 
intended angular field of the lens itself. Dur- 
ing measurement, the light shall traverse the 
lens in the direction ordinarily employed in 
photography. 

13.1.4 The lens should be carefully exam- 
ined before calibration to ensure that there 
are no shiny regions in the barrel which would 
lead to flare or unwanted stray light, since 
this would vitiate the measurements badly. 
The lens surfaces should be clean. 

13.2 Corner-to-Center Ratio. Having 
calibrated the stop markings of the lens on 
the T system by one of the methods to be de- 
scribed, the observer may, if desired, deter- 
mine in addition the ratio of corner illumina- 
tion to center illumination, at full aperture and 



* Specifically a tungsten filament lamp operating be- 
tween 2900 and 3200 degrees Kelvin. 

t A suitable cell is one having an S-3 surface, com- 
bined with a Corning 9780 glass filter about 2.5 mm 
thick. 



NOT APPROVED 



344 



October 1952 Journal of the SMPTE Vol. 59 



Proposed American Standard 

Aperture Calibration 
of Motion Picture Lenses 



PH22.90 



p. 7 of 10 pp. 



preferably at other apertures also. For this 
purpose the 3-mm (or IV-z-mm) hole shall be 
used first at the center of the field, and then 
moved outwards until its rim is touching the 
top and side limits of the camera gate. This 
distance is shown in Table I. 



Table 



Gate, Mm 

35(16.03 x 22.05) 

16 ( 7.47 X 10.41) 

8 ( 3.51 x 4.80) 



Radial Shift of Hole, Mm 

11.5 

4.5 

2.0 



13.3 Extended-Source Method of 
T-Stop Calibration (distant object). 

13.3.1 This method of lens calibration has 
been described by Gardner 13 and Sachtle- 
ben, 9 the underlying theory being given by 
McRae. 4 It is based on filling the lens with light 
from an extended uniform source, and plac- 
ing a metal plate in the focal plane of the 
lens with a 3-mm hole (or 1.5-mm for 8-mm 
film) at its center. The light flux passing 
through the hole is measured by a photocell 
arrangement. This flux is then compared with 
the flux from the same source passing through 
the same hole from an open circular aperture 
of such a size and at such a distance from the 
plate that it subtends the desired angle 6 re- 
ferred to in equation (2) above. The greatest 
care is necessary to ensure that the extended 
source is really uniform, and also constant 
throughout the measurements. The open cir- 
cular aperture is used as the "ideal lens with 
100 per cent transmittance" referred to in 
Section 5.2. 

13.3.2 It should be noted that this proce- 
dure measures the T-stop Aperture Ratio of the 
lens directly, regardless of whether or not the 
lens is aplanatic. 

13.3.3 In practice, the photocell reading for 
each whole T-stop number is first determined 



for a series of open apertures, at a fixed dis- 
tance from the plate. The lens is then substi- 
tuted for the open aperture with the 3-mm 
hole accurately in its focal plane, and the iris 
of the lens is closed down until the photocell 
meter reading produced by the lens is equal 
to each of the successive open-hole readings. 
The full T-stop positions are then marked on 
the diaphragm ring of the lens. The intermedi- 
ate third-of-a-stop positions may be found 
with sufficient accuracy by inserting a neutral 
density of 0.1 or 0.2 behind each open aper- 
ture in turn and noting the corresponding 
photocell readings. 

13.3.4 The following table of aperture di- 
ameters may be useful. They are based on a 
distance of 50 mm from aperture to plate. (It 
is important to remember the difference be- 
tween sine and tangent, and that the aper- 
ture diameter is not found merely by dividing 
50 mm by the T number.) 

Table II 

Value of = 

Cosec~l Diameter of 

Desired (2 X T number), Aperture = 

T Number Degrees 1 00 tan f). mm 



0.5 

0.71 

1.00 

1.41 

2.00 

2.83 

4.00 

5.66 

8.00 

11.31 

16.00 

22.63 

32.00 



90 
45 
30 

20.708 

14.478 

10.183 

7.181 

5.072 

3.583 

2.533 

1.791 

1.266 

0.895 



oo 

100 

57.74 

37.80 

25.82 

17.96 

12.60 

8.88 

6.26 

4.42 

3.12 

2.21 

1.56 



13.3.5 A single set of apertures is sufficient 
to calibrate lenses of all focal lengths, since 
the only factor involved is sin 9, and that is 



NOT APPROVED 



October 1952 Journal of the SMPTE Vol. 59 



345 



Proposed American Standard 

Aperture Calibration 
of Motion Picture Lenses 



PH22.90 



fixed by the aperture used. The apertures 
should be bevelled to a sharp edge, and well 
blackened on both sides. 

13.3.6 The extended source should be uni- 
formly bright over its useful area to within 3 
per cent. (This can be tested with a suitable 
telephotometer, or a small hole in an opaque 
screen can be moved around in front of the 
source, and any consequent variations in 
photocell reading noted.) The source conveni- 
ently may be a sheet of ground glass covering 
a hole in a white-lined box containing several 
lamps mounted around the hole and shielded 
so that no direct light from the lamps falls on 
the ground glass itself. 

13.3.7 The photocell receiver conveniently 
may be of the phototube type with a simple 
direct-current amplifier.* Care must be taken 
to ensure that the phototube sensitivity and 
the line voltage do not change between mak- 
ing readings on the open aperture and on the 
lens itself; to guard against this, some con- 
venient turret arrangement is desirable with 
the lens on one side and the open aperture on 
the other so that the two may be interchanged 
and compared immediately with each other 
by merely turning the turret. 

13.3.8 To measure the corner-to-center il- 
lumination ratio, then lens is set in position and 
the 3-mm hole and the photocell are displaced 
laterally by the desired amount. The photocell 
reading is noted at axial and corner positions, 

* Suitable systems are the "Electronic Photometer" 
model 500 (Photovolt Corporation, 95 Madison Ave., 
New York, N. Y.), and the "Magnephot" (W. M. 
Welch Scientific Co., 1515 Sedgwick St., Chicago, III.). 
It is felt that a barrier-layer cell, although desirable 
for reasons of simplicity, has insufficient sensitivity for 
accurate determinations of the smaller apertures un- 
less a galvanometer of exceptionally high sensitivity 
is employed. 



p. 8 of 10 pp. 

and the corresponding light ratio found from 
a calibration curve of the photocell meter. 

13.4 Collimated Source Method of 
Lens Calibration. 

13.4.1 This method has been described by 
Daily n and Townsley, 14 the underlying theory 
being embodied in Section 5 above. Light from 
a small source (a 5-mm hole covered with opal 
glass and strongly illuminated from behind) is 
collimated by a simple lens, or an achromat if 
preferred, of about 15 inches focal length and 
2 inches aperture. This gives a collimated 
beam which will be focused by the test lens to 
form a small disk of light in its focal plane. 
This circle of light will be less than the pre- 
scribed limit of 3-mm diameter for all lenses 
under 9 inches in focal length. Uniformity of 
the collimated beam can be checked by mov- 
ing a small hole in an opaque screen across 
the beam, and any variations in the photocell 
reading noted. 

13.4.2 For the comparison unit, an open 
aperture is used, of diameter equal to the 
focal length of the lens divided by the desired 
T number. This aperture is first mounted in 
front of an integrating sphere with the usual 
photocell detector, and the light from the col- 
limator is allowed to enter the aperture. The 
aperture plate is now replaced by the lens, 
the iris diaphragm is closed down to give the 
same photocell reading, and the T-stop num- 
ber is engraved on the iris ring. The inter- 
mediate thirds of stops can be added by using 
0.1 or 0.2 density filters as in the method of 
Section 13.3.3. 

13.4.3 To guard against drift and line-volt- 
age variations which might occur between the 
readings on the comparison aperture and on 
the lens, it is convenient to leave the known 
standard aperture in place in front of the 
sphere, and to insert the lens into the beam in 



NOT APPs?OVED 



346 



October 1952 Journal of the SMPTE Vol. 59 



Proposed American Standard 

Aperture Calibration 
of Motion Picture Lenses 



PH22.90 



such a position that the little image of the 
source falls wholly within the standard aper- 
ture. The meter reading should then remain 
the same no matter whether the lens is in or 
out of the beam. A second plate with a 3-mm 
aperture should be placed over the compari- 
son aperture while the lens is in place to stop 
any stray light which may be reflected from 
the interior of the lens. 

13.4.4 It should be noted particularly that if 
this method is used, the focal length of the lens 
must be measured separately, and a suitable 
set of open apertures constructed for use with 
it. However, by suitable devices, one single 
set of fixed apertures may be used for all 
lenses, as described by Townsley. 14 

13.4.5 It should also be noted that this pro- 
cedure measures f number as the ratio of f/D, 
and the measurement is thus influenced by the 
state of correction of the lens in regard to 
spherical aberration and sine condition. 

13.4.6 The corner-to-center ratio at any de- 
sired aperture can be conveniently determined 
by simply rotating the lens through the de- 
sired field angle (/> and comparing the photo- 
cell reading with its value for the lens axis. 
The light-flux ratio can then be read off a cali- 
bration curve for the photocell system, and 
converted to the desired corner-to-center illum- 
ination ratio by multiplying it by cos 3 <. (Note 
that this procedure will be correct only in the 
absence of distortion, but no motion picture 
lens is likely to have enough distortion to cause 
any significant error.) 

13.5 T-Stop Calibration at Finite 
Magnification. 

13.5.1 To use the extended source method 
(see Section 13.3), it is only necessary to 
mount the metal plate at the desired image 
distance from the lens instead of placing it in 



p. 9 of 10 pp. 

the focal plane. The open apertures used for 
comparison must be calculated to have an 
opening corresponding to the desired Equiva- 
lent f number multiplied by (1 + m). This is be- 
cause we are really comparing the illuminance 
given by the lens with the Effective f number 
of the open hole, but the engraving must be 
done at each standard step of the Equivalent f 
number (see Section 1 2.2.) 

1 3.5.2 The collimated source method cannot 
be used to calibrate a lens at finite magnifica- 
tion. 

References 

General 

1 . A. C. Hardy, "The distribution of light in optical 
systems," J. Frank. Inst., vol. 208, pp. 773-791, Dec. 
1929. 

2. A. C. Hardy and F. Perrin, "Principles of Optics," 
McGraw-Hill, New York, 1932, p. 411. 

3. L. C. Martin, "Applied Optics," vol. 2, Pitman, 
London, 1932, p. 210. 

4. D. B. McRae, "The measurement of transmission 
and contrast in optical instruments," J. Opt. Soc. 
Amer., vol. 33, pp. 229-243, Apr. 1943. 

Lens Calibration 

5. G. W. Moffitt, "Determining photographic absorp- 
tion of lenses," J. Opt. Soc. Amer., vol. 4, pp. 83-90, 
May 1920. 

6. J. Hrdlicka, "Measuring the effective illumination 
of photographic objectives," Jour. SMPE, vol. 14, pp. 
531-553, May 1930. 

7. D. B. Clark and G. Laube, "Twentieth Century 
camera and accessories," Jour. SMPE, vol. 36, pp. 
50-64, Jan. 1941; also U.S. Patent 2,334,906 (filed 
Sept. 1940, issued Nov. 1943). 

8. E. W. Silvertooth, "Stop calibration of photo- 
graphic objectives," Jour. SMPE, vol. 39, pp. 119-122, 
Aug. 1942. 

9. L. T. Sachtleben, "Method of calibrating lenses," 
U.S. Patent 2,419,421 (filed May 1944, issued April, 
1947). (Note: This patent is held by RCA, which has 
expressed willingness to grant a paid-op license for a 



NOT APPROVED 



October 1952 Journal of the SMPTE Vol. 59 



347 



Proposed American Standard 

Aperture Calibration 
of Motion Picture Lenses 



PH22.90 



p. 10 of 10 pp. 



nominal fee. See Jour. SMPTE, vol. 56, pp. 691-692, 
June 1951.) 

10. E. Berlant, "A system of lens stop calibration by 
transmission," Jour. SMPE, vol. 46, pp. 17-25, Jan. 
1946. 

11. C. R. Daily, "A lens calibrating system," Jour. 
SMPE, vol. 46, pp. 343-356, May 1946. 

12. A. E. Murray, "The photometric calibration of 
lens apertures," Jour. SMPE, vol. 47, pp. 142-151, 
Aug. 1946. 

13. I. C. Gardner, "Compensation of the aperture 
ratio markings of a photographic lens for absorption, 
reflection, and vignetting losses," Jour. SMPE, vol. 49, 
pp. 96-110, Aug. 1947; also J. Res. Nat. Bur. Stand., 



vol. 38, pp. 643-650, June 1947 (Research Paper 
RP 1803). 

14. M. G. Townsley, "An instrument for photometric 
calibration of lens iris scales," Jour. SMPE, vol. 49, 
pp. 111-122, Aug. 1947. 

15. F. G. Back, "A simplified method for the preci- 
sion calibration of effective i stops," Jour. SMPE, vol. 
49, pp. 122-130, Aug. 1947. 

16. F. E. Washer. "Errors in calibrations of the f 
numbers," Jour. SMPE, vol. 51, pp. 242-260, Sept. 
1948; also J. Res. Nat. Bur. Stand., vol. 41, pp. 301- 
313, Oct. 1948 (Research Paper RP 1927). 

17. A. E. Murray, "Diffuse and Collimated T-Num- 
bers," Jour. SMPTE, vol. 56, pp. 79-85, Jan. 1951. 



NOT APPROVED 



348 



October 1952 Journal of the SMPTE Vol. 59 



International Standardization 



By F. T. BOWDITCH, SMPTE Engineering Vice-President 



ON LAST JUNE 9, 10 and 11 at Columbia 
University, the first meetings of Tech- 
nical Committee 36 on Cinematography 
of the International Organization for 
Standardization were held. This is 
the standards group charged with the 
preparation of world standards in fields 
of cinematography, under the Secretariat 
of the American Standards Association. 
A following report by Henry Kogel 
will give details of the several subjects 
discussed. We will consider here our 
general impressions of this very interest- 
ing event. 

Contrary to the final feeling of a 
worth-while job well done, those of us 
from the United States who took part 
in this affair did so largely from a sense 
of duty to the Secretariat responsibilities 
of the ASA. None of us had any pre- 
vious experience in international de- 
liberations of this sort, and we were 
uncertain as to how much could be ac- 
complished. At the end of three days 
of close association with our foreign 
colleagues, however, the opinion was 
enthusiastically unanimous that the 
meetings had been very much worth 
while; the only complaint to come to 
my attention concerned the schedule, 
in which only two days had been allo- 
cated to TC36. Arrangements were 
made on the second day to continue for 
a third, and everyone felt that a full 
week could have been spent with profit; 
as a matter of fact, with a series of group 
meetings burning the midnight oil on 
both Monday and Tuesday evenings, a 
good week's work was actually crowded 
into those three days. 

In addition to the U.S. delegation, the 
meetings were attended throughout by 



representatives of Canada, France, Ger- 
many and the United Kingdom. A 
Belgian representative joined us occa- 
sionally, and a space was continually 
reserved for the U.S.S.R., whose dele- 
gates were somewhere about, but 
scheduled uncertainly between cine- 
matography and other concurrent meet- 
ings. The Russians never did visit us, 
which was a matter for some disappoint- 
ment curiosity-wise, although the com- 
plication of a second translation of all 
remarks would undoubtedly have slowed 
our progress. As it was, the remarks of 
the delegate from France, M. Jean Vivie, 
were always made in his native tongue, 
with frequent pauses for translation 
into English; while the remarks of all 
other delegates in English were trans- 
lated into French for M. Vivie. This 
would at first seem to delay things 
immeasurably, but we were fortunate 
in having a most capable interpreter, 
Mr. L. Foy, whose repertoire included 
perhaps ten languages any one of which 
he could translate extemporaneously 
and unhesitatingly into any other. He 
soon developed an amazing knowledge 
of motion picture technology and so 
operated with the highest efficiency. 

The formal meetings were opened on 
Monday morning, June 9, by Vice- 
Admiral G. F. Hussey, Jr., Managing 
Director of the ASA. He introduced 
D. E. Hyndman, who delivered the 
welcoming address, calling attention 
not only to the great importance of 
international standards in facilitating 
world trade, but pointing out the forth- 
coming significance of television as an 
international force, and predicting a 
growing interest of TC36 in world 



October 1952 Journal of the SMPTE Vol. 59 



349 



standards for this specialized form of 
motion pictures. 

Dr. L. Knopp, delegate from the 
United Kingdom and President of the 
British Kinematograph Society, then 
proposed that the writer be elected 
as Chairman of the meeting, which was 
promptly done. This responsibility 
was approached with some uncertainty, 
but was soon exercised with greater 
confidence as the fine cooperative spirit 
of the delegates became apparent, and 
as the bilingual machinery operated 
with much greater smoothness than we 
had anticipated. Mr. W. Rambal of 
the central ISO office in Geneva sat at 
the Chairman's right in the first sessions, 
to offer helpful advice on parliamentary 
matters as needed. 

As things developed, the formal 
meetings of the whole Committee were 
soon abandoned in favor of a series of 
six Working Group meetings on as 
many different subjects. These were 
attended by all the foreign delegates 
and by a limited number of U.S. dele- 
gates most interested in each particular 
subject. Chairmanships of these Work- 
ing Groups were delegated to the 
French, German and United Kingdom 
representatives, as well as to the U.S., 
and all were conducted in a most 
efficient manner. Jean Vivie of France, 
Dr. Leo Busch and Wilhelm Waegelein 
of Germany, and Dr. L. Knopp and 
H. L. Griffiths of England worked tire- 
lessly and conscientiously with all these 
groups, till late at night on Monday and 
Tuesday, and starting again early each 
morning. Gerald Graham of Canada 
was also present, but only as an observer 
since his country is not represented as 
a full working member of TC36; Mr. 
Foy, our indefatigable translator, was 
ever-present to bridge the language 
barrier. The U.S. delegation of 20 
persons, ably headed by Dr. D. R. 
White, chairman of ASA Sectional 
Committee PH22 on Motion Pictures, 
had a somewhat easier time of it, with 
a different small number at each group 



meeting. The many months of prepa- 
ration by PH22 and by the several 
Engineering Committees of SMPTE 
proved exceedingly helpful here, as did 
the active participation of The Motion 
Picture Research Council. W. F. Kelley 
of the Council cooperated in all the 
group meetings, giving much helpful 
advice where motion picture studio 
considerations were involved. 

Minutes of each meeting and copies 
of all resolutions were prepared in time 
for distribution at the next session, 
mimeographed both in French and in 
English. This required that an English 
version be prepared at the earliest 
possible moment. Henry Kogel, Staff 
Engineer of SMPTE, was of much 
service here, cooperating with J. W. 
McNair, Miss Virginia Kelly and Miss 
Carolyn Locher of ASA to get all of our 
deliberations correctly recorded. 

At the final formal meeting of TC36 
on Wednesday afternoon, it was agreed 
that all the Working Groups should be 
continued on a more permanent basis, 
under the chairmanships first assigned. 
It seems certain that cooperation via 
correspondence will now be very much 
more effective than before these personal 
acquaintanceships were made. Cer- 
tainly the foreign delegates gave every 
evidence of a high degree of competence 
and sincerity, and in all instances were 
very well prepared to discuss the various 
matters on the agenda. 

The U.S. delegates had also come well 
prepared and with open minds, as 
witness the agreement to recommend 
as a World Standard a picture-to-sound 
separation of 21 frames for 35mm film. 
The present American Standard specifies 
this distance to be only 20 frames, and 
any change at first seemed to be an alto- 
gether futile attempt to change a well- 
established U.S. practice. It soon de- 
veloped, however, that the U.S. practice 
is in fact to use the 21 -frame separation: 
projectors are threaded at 20-frames, 
but the studios adjust the sound-to- 
picture separation on the film to, give 



350 



October 1952 Journal of the SMPTE Vol. 59 



synchronization to an observer seated 
50 ft from the screen. Some years 
ago this 21 -frame French proposal was 
received in the U.S. via correspondence, 
and circulated here for comment over 
a period of months, with unanimous 
agreement that it would be impractical 
for the U.S. to change. A half-hour's 
direct conversation with the French, 
English and German delegates brought 
out the fact noted above, that the U.S. 
has been using this proposal all along 
only the standard itself needs to be 
changed to bring everything into agree- 
ment! 



The opportunity of serving as the 
chairman of this first meeting of ISO/ 
TC36, although approached with some 
uncertainty, is looked back on with 
deep appreciation. This was a most 
heartening experience, and all who 
contributed to these meetings have the 
right to feel that the work of TC36 has 
now been given a most effective start. 
When men of good purpose sit down 
together and talk things over, much 
can be accomplished, as witness the 
following report by Henry Kogel. We 
are proud and happy to have played 
a part. 



Agenda and Accomplishments of 
ISO/TC 36 Meeting 

By HENRY KOGEL, SMPTE Staff Engineer 



THE PRECEDING REPORT on international 
standardization by F. T. Bowditch has 
clearly outlined the general aspects 
of the three-day meeting, June 9-11, 
of Technical Committee 36 on Cine- 
matography of the International Organi- 
zation for Standardization (ISO/TC 
36). It is, therefore, the intent to pre- 
sent here only the specific details con- 
sidered and the concrete results to date. 
The draft agenda was considered 
first, then amended slightly. It is 
given below in its final form along with 
the Working Group associated with each 
item. 

1. Welcoming Remarks, D. E. Hynd- 
man 

2. Introduction to Those Present, G. 
F. Hussey, Jr. 

3. Opening Remarks by the Chairman, 
F. T. Bowditch 

4. Approval of Agenda 

5. Review of Scope 



6. Dimensions of Raw Stock Work 
Group 1, chaired by D. R. White, 
United States 

7. Definition of Safety Film Work 
Group 2, chaired by Leslie Knopp, 
United Kingdom 

8. Emulsion and Sound Record Posi- 
tion in Cameras and Projectors 
Work Group 3, chaired by Leo 
Busch, Germany 

9. Dimensions and Location for Sound 
Records and Scanning Area Work 
Group 4, chaired by Malcolm 
Townsley, United States 

10. Location and Size of Picture Aper- 
tures in Cameras, Projectors and 
Printers Work Group 5, chaired 
by Jean Vivie, France 

11. Standards Relative to Projection 
Halls Work Group 6, chaired by 
Leslie Knopp, United Kingdom 

12. Review of Program of Work 



Bowditch and Kogel: International Standardization 



351 



In the discussion on scope, the French 
delegate proposed a new version. Modi- 
fications were offered and the following 
scope was approved for submittal to 
letter ballot of TC36. 

"The committee shall formulate defi- 
nitions, dimensions, methods of 
measurement and test, and performance 
characteristics related to materials and 
apparatus used in silent and sound mo- 
tion picture photography, in sound 
recording and reproduction and in 
laboratory work, also, standards relating 
to the installation and characteristics 
of projection and sound reproduction 
equipment. 

"Collaboration is to be established 
with all other Technical Committees 
working on related questions and es- 
pecially with the Committees ISO/TC 
42 Photography and ISO/TC46 
Documentation." 

The previous scope 'is offered for 
comparison purposes: 

"The formulation of definitions, di- 
mensional standards, methods of test, 
rating and performance characteristics 
of materials and devices used in silent 
and sound motion picture photography 
and in sound recording and processing 
and reproduction in connection there- 
with. Collaboration is to be established 
with other Technical Committees, 
especially with ISO/TC46 Docu- 
mentation, in work on photographic 
reproduction." 

After providing each member nation 
an opportunity to make a general state- 
ment on agenda items 6-11, the chair- 
man appointed Work Group chairmen 
and the remainder of the sessions were 
devoted primarily to the detailed con- 
siderations of the six Work Groups. 
The conclusions reached in each Group 
are presented below. 

Dimensions of Raw Stock 

It was unanimously agreed to recom- 
mend to ISO/TC36 that the secretariat 
prepare a Draft ISO Proposal for letter 
ballot action of all members on Cutting 



and Perforating Dimensions for 35mm 
Motion Picture Positive Raw Stock to 
be based upon the American Standard 
Z22. 36-1 947 with the changes indicated 
below. 

(1) Dimension A to read 

1 -2-70 + 0.000 . , -2C nn + 0.00 

1. 378 _ 0.002 inch 35.00 - o.os mm 

(2) Dimension L to read 

18.70 0.15 inch 475.00 =b 0.40 mm 

(3) Dimension R to read 

0.50 millimeter, provided that the 
secretariat finds that this is the proper 
way to express correspondence with 
0.020 inch. 

(4) Dimension G to be expressed as 
shown in the French Standard 
NFS 24-003 with the drawing of the 
type given therein but with the 
format altered to show lines re- 
ferring to bottom edges of perfora- 
tions rather than center lines. 

(5) The footnotes in Z22.36-1947 indi- 
cated by an asterisk and a dagger, 
and the appendix, are to be deleted. 

(6) Dimension symbol "I" to be changed 
to "F." 

It was also unanimously agreed to 
recommend to ISO/TC36 that the 
secretariat prepare two Draft ISO 
Proposals on Cutting and Perforating 
Dimensions for 16mm Silent and Sound 
Motion Picture Negative and Positive 
Raw Stock, based upon the American 
Standards Z22.5-1947 and Z22.12-1947, 
with the following changes: 

(1) Dimension A to read 

0.628 0.001 inch 15.95 t HI mm 

(2) The drawing used to show dimension 
G in Z22.5 to follow French practice 
paralleling the 35mm presentation 
adopted from the French Standard 
NFS 24-003, Dimensions of 35mm 
Positive Raw Stock, With Positive 
Perforations. 

(3) Dimension symbol "I" to be changed 
to "F" in Z22.5. 

(4) Omit notes indicated by asterisk 
and dagger. 



352 



October 1952 Journal of the SMPTE Vol. 59 






(5) Omit appendix. 

(6) Add a new note reading 
"Experience shows that it is common 
for film to expand when exposed to 
high relative humidity. Allowance 
should be made for this factor in 
equipment design and in no case 
should the equipment design fail to 
accommodate film width of 0.630 
inch, 16.00 mm." 

A specification for film thickness 
discussed by the working group but 
no agreement was reached. The matter 
was left for further discussion and study. 

Definition of Safety Film 

It was initially agreed that an inter- 
national standard for the definition, test 
and identification of safety film should 
be established. 

One of the U.S.A. delegates believed it 
would be desirable that any ISO 
standard for 32mm, 16mm and 8mm 
motion picture film should stipulate the 
use of a safety base only. The proposal 
appeared to raise national statutory 
and legal questions which would call 
for investigation and consideration. 

The working group noted that the 
research which had been conducted in 
the United Kingdom had established a 
simple form of test which might replace 
the more elaborate laboratory tests of 
the current American Standard Defini- 
tion for Motion Picture Safety Film, 
Z22.31-1946. A demonstration of the 
apparatus was given and the members 
thought the United Kingdom test 
worthy of study. The United Kingdom 
undertook to prepare and circulate 
working drawings and particulars to 
enable each country to make its own 
apparatus and carry out confirmatory 
tests. 

France and Germany, however, de- 
sired the earliest possible establishment 
of an international standard and sug- 
gested that the current American Stand- 
ard, which was virtually a reproduction 
of the ISA proposal of 1936, should be 



considered for adoption by the ISO 
for a three-year period. While not 
seeing any urgent need for this, the 
United States representatives said they 
would not wish to oppose the adoption 
of this course. The United Kingdom 
delegates had no power to commit their 
country but only to express the view that 
the 1936 ISA proposal was too elaborate, 
was out-of-date and the time was ripe 
for a new specification to be formulated. 

It was understood that the ISO was 
willing to circulate ISA proposals and 
recommendations which could be used 
nationally pending the agreement on an 
international standard. 

Agreement was finally reached that 
the Definition for Motion Picture Safety 
Film, Z22.31-1946, be submitted to 
ISO/TC36 for letter ballot action. 

Emulsion and Sound Record Positions 
in Cameras and Projectors 

The working group agreed to recom- 
mend to ISO/TC36 that the secretariat 
prepare a Draft ISO Proposal in- 
corporating the technical content of the 
American Standards listed below with 
the modifications indicated: 

Emulsion and Sound Record Positions 

in Camera for 35mm Sound Motion 

Picture Film, Z22.2-1946, 
Emulsion and Sound Record Positions 

in Projector for 35mm Sound Motion 

Picture Film, Z22.3-1946, 
Delete paragraphs 2 and 3, reference 
to guided edge and footnote. Add 
identification of sound record (shaded 
area). 

Emulsion Position in Camera for 16mm 

Silent Motion Picture Film, Z22.9- 

1946, 
Emulsion Position in Projector for Direct 

Front Projection of 16mm Silent 

Motion Picture Film, Z22. 10-1 947, 
Emulsion Position in Camera for 8mm 

Silent Motion Picture Film, Z22.21- 

1946, 
Emulsion Position in Projector for Direct 

Front Projection of 8mm Silent 



Bowditch and Kogel: International Standardization 



353 



Motion Picture Film, Z22.22-1947, 
Delete paragraph 2 and footnote. 

Emulsion and Sound Record Positions 
in Camera for 16mm Sound Motion 
Picture Film, Z22. 15-1 946, 
Delete paragraph 2, footnote and ref- 
erence to guided edge. Also delete 
paragraph 3, but the technical substance 
of this paragraph is considered suitable 
for incorporation in a more suitable 
place. Add identification of sound 
record (shaded area). 

With regard to Z22. 16-1 947, the 
working group decided that at present 
it did not seem desirable to consider 
this for international adoption since 
prints were made with the emulsion 
position on either side and there was 
little likelihood of universal acceptance 
of a single standard at this time. 

The working group discussed at some 
length the question of projection speed 
of 24 or 25 frames per second, but did 
not reach any decision. 

Dimensions and Locations for Sound 
Records and Scanning Area 

Work Group 4 recommended that 
five American Standards be prepared 
by the secretariat for circulation as 
Draft ISO Proposals, two without 
change : 

Z22.69-1948, Sound Records and Scan- 
ning Area of Double-Width Push-Pull 
Sound Prints, Normal Centerline 
Type, 

Z22.70-1948, Sound Records and Scan- 
ning Area of Double-Width Push-Pull 
Sound Prints, Offset Centerline Type ; 

and three with the modifications in- 
dicated below: 

Z22.40-1950, Dimensions and Locations 
for Sound Records and Scanning 
Area of 35mm Sound Motion Picture 
Prints 

(1) The distance from the edge of the 
film to the centerline of the sound 
record shall be changed from 6.17 



0.02 mm to 6.19 0.02 mm (0.244 
0.001 in.). 

(2) The distance from the edge of the 
film to the inner edge of the printed 
area shall be changed from 7.75 
0.05 mm to 7.83 0.05 mm (0.308 
0.002 in.) . (This change was proposed 
by the French delegate on the basis 
that difficulties are being experienced 
in France with a white line between 
sound track and picture printed areas. 
The United Kingdom delegation re- 
served judgment on the dimension 
in (1) and (2) above, but approves 
the circulation of the draft.) 

(3) In the specification "Distance 
between sound and corresponding 
picture" change "20 J frames" to 
"21 frames frame." (When the 
distance from the center of the pro- 
jector gate to the sound scanning point 
is 20 frames, the picture and sound 
will be in synchronism for an observer 
at a distance of 50 feet, and with 
French practice, which is based on a 
measured distance of 21 frames be- 
tween picture and sound on the film 
itself, and therefore allows for syn- 
chronizing the picture to suit an aver- 
age audience size.) 

(4) Delete the third footnote. 

(5) Delete the dimension and all 
reference to the height of the scanned 
area. 

Z22.41-1946, Sound Records and Scan- 
ning Area of 16mm Sound Motion 
Picture Prints 

(1) Change the tolerance on the 
width of the sound record for full 
width variable-density record from 
0.080 0.001 in. to 0.080 oiooi in. 

(2) Delete the present footnote. 

(3) Add a new footnote reading: 
"The width of the 16mm sound record 
is derived by reducing the corre- 
sponding 35mm dimensions by a ratio 
of 1.2 to 1.0 in. 

(4) Add a new paragraph : "Distance 
between sound and corresponding 
picture the sound record shall pre- 



354 



October 1952 Journal of the SMPTE Vol. 59 



cede the center of the corresponding 
picture by a distance of 26 frames 
| frame." 

PH22.86, Dimensions for 200-Mil Mag- 
netic Sound Tracks on 35mm and 
17^mm Motion Picture Film (a 
Proposal well on its way to becoming 
an American Standard). 

(1) Revise the drawing and dimen- 
sions to show a dimension from the 
outer edge of the sound record area 
to the edge of the film 6.0 0.05 
mm (0.236 0.002 in.) on each edge 
of the film, and delete all other di- 
mensions and all reference to the 
track in the center of the film, re- 
numbering Track 3 to Track 2. 
(The United Kingdom delegation 
was unable to associate itself fully 
with this resolution as being the best 
solution of the current practices in 
America, France and in the United 
Kingdom, and offered alternative 
proposals (which, however, were 
not accepted) on the dimension of 
0.345 inch 0.005 or 0.345 inch 
0.006, as the location of the centerline 
of the sound record relative to the 
edge of the film.) 

(2) Delete paragraph 7. 

(3) Add a note to Paragraph 6: 
"When the film is turned end for 
end, Track 2 occupies the position of 
Track 1." 

Location and Size of Picture Apertures 
in Cameras, Projectors and Printers 

The chairman of Group 5 has not as 
yet submitted the report of the con- 
clusions reached by his group. This 
information will be published in a 
future issue of the Journal as soon as 
it is received. 

Standards Relating to Projection Halls 

The members of Work Group 6 had 
each presented at their meeting a sum- 
mary of the requirements and values in 
their published and draft standards on 
the subject of screen brightness. Refer- 
ence was also made to the resolution 



of the CIE (International Commission 
on Illumination) at its meeting in 
Stockholm in 1951. It was agreed to 
restrict discussion to enclosed cinema 
auditoriums. 

The members noted that the various 
countries were now giving consideration 
to such factors as : the screen brightness 
measurement made from any seat in the 
auditorium, the diversity of luminance 
between the side and center of the 
screen, interference of luminance by 
stray light, the method of measurement 
and the type of instruments to be used. 
The views of the delegates on these 
questions were diverse and in some of the 
countries research and investigation 
were still proceeding. 

Differing opinions were also expressed 
as to the desirability of adopting the 
luminance range and the diversity factors 
of the CIE Stockholm meeting. It was 
noted that the United States and the 
United Kingdom expressed their lumi- 
nance values in foot-Lamberts while 
France, Germany and the CIE resolu- 
tion expressed values in metric units. 
It was also noted that, notwithstanding 
these divergencies, the quantitative dif- 
ference in the various specifications and 
in the CIE resolution were not great. 

In view of the research and investi- 
gation still proceeding in the various 
countries, it was the general consensus 
that it was not opportune at the present 
ISO/TC36 meeting to attempt to 
draft an ISO proposal. It was agreed, 
therefore, that each country should 
proceed with its own investigations and 
revision of its own standards, if desired, 
and that there should be a postal ex- 
change of information between the 
countries, so that at the next meeting of 
ISO/TC36 the present discussions 
might be resumed and an ISO proposal 
drafted. 

The working group regretted that 
time did not permit any discussion on the 
remaining subjects such as projection 
rooms and projection screens listed under 
item 11 of the agenda. 



Bowditch and Kogel: International Standardization 



355 



Organization of the San Francisco Subsection 



This brief outline of the organization of the 
San Francisco Subsection of the Society 
may be of interest and assistance to 
similarly situated groups in other localities. 

The San Francisco Subsection began 
as the expression of a desire of a number 
of the individual members in the Bay 
Area to have some form of local activity 
and participation in the affairs of the 
Society. The Conventions held alter- 
nately in Hollywood provided some 
advantage but in general most of the mem- 
bers gained from their membership only 
the published Journal. 

Many informal discussions had been 
held during 1951 regarding the prac- 
ticability of setting up some form of local 
group and these culminated in the forma- 
tion of the present organization. Edwin 
W. Templin and Dr. Charles R. Daily 
were particularly helpful in presenting 
our plan to the Board of Governors and 
securing its approval. The Constitution 
of the Society does not specifically provide 
for subsection organization but neither 
does it forbid it, and, by the latter liberal 
view, the San Francisco group was au- 
thorized to form the subsection of the 
Pacific Coast Section at the meeting of 
October 13, 1951. 

Upon receiving formal notice of this 
action, all of the members of the Society 
residing in the Bay Area were notified by 
mail and the organizational meeting of the 
subsection was held November 30, 1951. 
Dr. Daily addressed the group at this 
meeting and acted as chairman, represent- 
ing the parent section. Election of officers 
resulted in the following roster for 1952: 

Chairman, Paul A. Williams 
Vice-Chairman, William A. Palmer 
Secretary-Treasurer, George Mathiesen 
Program Chairman, John B. Steiger 

During the first half of the year the sub- 
section has held three meetings, the 
programs of which were as follows : 

February 21: "Production of a Pilot 
Kinescope for the Standard Hour" pre- 
sented by a panel consisting of Warren 
Andersen, A. F. Michaelis and W. A. 
Palmer. 

356 



April 17: "TV Picture Sizes," a tape 
recording of papers and discussion from a 
meeting of the Pacific Coast Section in 
Hollywood. 

May 22: "Creative Directions in Color 
Photography" presented by Ralph Evans 
of Eastman Kodak Company. 

Attendance at these meetings has been 
from 20 to 50, which, although perhaps 
not too impressive, represents a large 
percentage of the total group membership. 

Although there was no expressed plan 
of suspending meetings during the summer, 
the usual circumstances have conspired 
to prevent or delay the fulfillment of our 
anticipated plans. Meetings are planned 
for the fall and winter and we hope to end 
the first year of operation at a peak of 
activity. 

The effect of an actively functioning local 
group on membership recruiting activity 
has been very gratifying. It is conserva- 
tively estimated that we have added twice 
the number of new members since be- 
ginning local operation compared with 
the previous like period. It is also 
interesting to note that, although the 
present interest in the television field has 
probably encouraged activity and increased 
our local membership, there has been 
enthusiastic interest among members in 
the motion picture industry. 

Whether or not the time is ripe for the 
San Francisco group to plan on an early 
change to independent section operation 
cannot yet be determined. At the end 
of this year officers will be elected for the 
coming term and that question fully 
discussed. 

We have not been as active as we had 
hoped but we are certain that our activity 
will increase rather than diminish. It 
would be a real help if more assistance 
could be provided in securing program 
material. The experiment we made with 
the use of tape recorded material was con- 
sidered successful but for some reason or 
another we have had some difficulty in 
arranging for additional recorded program 
material. It is noted that the IRE Audio 
Group has set up a similar plan with a 



central tape exchange and this method 
might be worth consideration. 

The Subsection expenses are a very 
minor consideration, for, aside from the 
cost of mailing program announcements, 
no other expense has been incurred. The 
parent Section advanced a sum sufficient 
to cover this and other incidental expense. 
Meeting places, projection or reproduction 
equipment and preparation of meeting 
notices have been provided by various 
members through the courtesy of their 
business connections. 

We are firmly of the opinion that the 



Society ' as a whole and its individual 
members have much to gain by establish- 
ment of other subsections. The time has 
long since passed when New York and 
Hollywood represented a concentration 
of motion picture and television activity 
to the exclusion of all other areas. The 
Society should provide some service to its 
members in other areas beyond the pub- 
lication and distribution of its Journal and 
we are of the opinion that the organization 
plan we have followed provides a means 
toward that end. Paul A. Williams, 341 
Hazelwood Ave., San Francisco 12, Calif. 



Book Review 



Color in Business, Science and 
Industry 

By Deane B. Judd. Published (1952) by 
John Wiley, 440 Fourth Ave., New York 
16. 401 pp. 106 illus. 6 X 9| in. 
Price 16.50. 

Here is a most useful and valuable book 
by Dr. Deane B. Judd, Chief of the 
Colorimetry Unit of the National Bureau 
of Standards. During his twenty years 
with the Bureau he has come in contact 
with hundreds of industrial colorimetric 
problems. This book reflects his great 
experience along these lines as well as 
the many contributions which Dr. Judd 
has made to the science of color. It is 
an ambitious undertaking to attempt a 
book on color that would appeal to busi- 
ness, to science, and to industry; but 
through Dr. Judd's long association with 
all three groups he has succeeded re- 
markably well. 

The businessman may enjoy the very 
readable Part I with its emphasis on the 
eye, the customer, and what the customer 
sees. He may then profit by scrutinizing 
the excellent introductions and summaries 
in each of the other sections in the re- 
mainder of the book, leaving the study of 
the technical details in these sections to 
others. However, industrial engineers and 
research workers in the field of color will 
find the entire work valuable because of 
the fusion of the practical problems with 
their theoretical aspects and the engineer- 



ing or technical solutions to them. In 
fact, the book is mainly directed at this 
group, and excels any other work in telling 
the story of the tools and techniques 
available to workers in the field. 

The book is divided into three parts. 
Basic facts pertaining to the science of 
color are given in Part I. Here the 
author explains the functioning of the eye, 
the characteristics and effects of abnormal 
vision, the methods of color matching, 
and the aspects of color. It is clearly 
shown that perception of color bridges 
many sciences. This is, however, treated 
in practical fashion as shown by the 
section titles: "Chemical Pigments and 
Dyes," "Physical Radiant Energy in 
the Spectrum," "Psychological The Cus- 
tomer's Angle," and "Psychophysical 
How to Predict What the Average Cus- 
tomer Will See." 

Part II, entitled "Tools and Tech- 
niques," comprises by far the largest 
portion of the book. Here are set down 
the principles and practices for spectro- 
photometry, colorimetry and colorimeters, 
reproduction of pictures in color, color 
standards, uniform color scales, and color 
languages. Some 130 pages are devoted 
to these last three. He gives an unusually 
fine presentation with clear explanations 
and evaluations of available sets of color 
standards for specifying or matching color, 
such as the Munsell Book of Color, the 
Villalobos Colour Atlas, the Color Har- 
mony Manual, and other systems. Color 

357 



cards or standards provided by various 
segments of industry such as the textile, 
printing ink, or paint industries, are also 
described. The glossary of color terms 
at the end of Part II will be most useful 
in that it collects in one place the terms 
and definitions for the most important 
color concepts used in American industry. 

Part III, "The Physics and Psycho- 
physics of Colorant Layers," thoroughly 
explores techniques for determining or 
forecasting the gloss and opacity or hiding 
power of colored layers. The major por- 
tion of this part is given over to the 
Kubelka-Munk analysis as applied to 
dyed textiles, paints, papers or pigmented 
plastics. Several mathematical tables 
necessary for such analytical solutions are 
included in the appendix which should 
prove useful to those interested in these 
materials. 

There is an excellent selection of ref- 
erences which includes the important 
work in the field for those who will wish 
to pursue the subject further, and also a 
fine index. 

Members of the SMPTE may be par- 
ticularly interested in the section entitled 
"Reproductions of Pictures in Color," 
in which Dr. Judd outlines the general 
problem and also demonstrates by a prac- 
tical example the use of the CIE tristimulus 
values and the color triangle to select 
practical working primaries, and thence 
to the determination of camera sensitivities 
for a typical color television system. This 
reviewer was particularly impressed by 
Dr. Judd's reasonable approach to the 
old question of the importance of art 
versus science in color reproduction. To 
quote : 



"An important question in reproduction 
of pictures in color is color fidelity how 
faithfully the colors of the original scene 
are reproduced. This is not the whole of 
the problem of producing pictures that 
the public will like. We know too little 
about what makes us see objects and 
people from the mosaic of colored patches 
presented to the eye from real scenes to 
state with confidence that a completely 
faithful reproduction (not yet achieved, 
by the way) would always look good. In 
fact, there are some who take the position 
that perfect color fidelity usually leads 
to poor pictures and should be avoided on 
purpose. They say that intentional sys- 
tematic deviations from fidelity can make 
the picture better than the original itself. 
This is adding art to science. But even 
if you intend to try to improve on the 
original scene, it is a great help to have a 
faithful reproduction to start with. You 
could not get very far with intentional 
improvements if the basic color fidelity 
of the picture was so poor that it would not 
yield any reds, for example, in the picture, 
or so poor that greens in the original 
scene were rendered as reds in the picture. 
So, reasonably faithful reproduction of 
colors must be built into any reproduction 
system, even if the final aim is to improve 
artistically upon the original scene by in- 
tentional deviations from color fidelity." 

With the increasing emphasis on color 
in motion pictures and television, an 
understanding of this concept is important. 

This book is highly recommended to 
all interested in color and its industrial 
applications. L. M. Bearing, Technicolor 
Motion Picture Corp., 6311 Romaine St., 
Hollywood 38, Calif. 



Journal on Microfilm 



Microfilm editions of the Journal of the SMPTE are now available to members and 
subscribers from University Microfilms, Ann Arbor, Mich., which records more than 
700 periodicals. Journal Volumes 54 and 55 (1950) are priced at $4.15 and Volumes 56 
and 57 (1951) cost $4.00 (this is the year that the Journal switched to the two-column 
format, with a saving in pages). If there were enough demand for it, University Micro- 
films would make positives for the years 1941-49. The present price for such positives is 
about a half cent per page, but this would be reduced with a larger number of customers 
to share the cost of the negatives. Readers may address inquiries to University Micro- 
films, 313 North First St., Ann Arbor, Mich. 



358 



Members and the Journal Overseas 



Echoes of the impact of the SMPTE and 
the Journal come back to us from overseas 
now and then and we should record 
them, just as we have been able earlier in 
this Journal to record the exchange of 
bases for international standardization. 

A recent letter from Vernon Jarratt, 
Manager of Mole-Richardson (Italia), 
Rome, prompts some quotation and nota- 
tion about the Society in Italy: 

"What I have noticed is the considerable 
increase in the circulation of the Journal 
in the three years that I have been a 
member. This is probably more notice- 
able to someone like myself who is in 
constant touch with the various technical 
heads than visible in your list of subscrip- 
tions, as a good deal of the 'circulation' is 
the literal circulation of a copy that travels 
from office to office and from desk to desk. 

"When Mole-Richardson opened here 
in 1948 the technical side of the industry 
was in a pretty primitive state all around, 
as indeed is obvious to anybody who, from 
a purely technical point of view, considers 
the films such as Rome Open City, Four Steps 
in the Clouds, Paisa, and the other films 
with which Italy first made its postwar 
name. This was partly due to destruction 
and looting during the war, and partly 
to the Fascist policy of autarchy which 
threw the Italian industry very much back 
on its own resources. 

"One incidental result of this was rather 
amusing. When we brought in the first 
'Brutes' in 1949 most cameramen refused 
to touch them, insisting that they could 
manage quite well with the 150-amp arcs 
to which they were already accustomed. 
One or two of the more enterprising (who, 
incidentally and not surprisingly, are also 
members of the Society) broke the ice, 
however, and the rest rapidly followed. 
The difference was very noticeable when, 
last year, we introduced Compact Source 
(mercury-cadmium) equipment for the 
first time. Although this represents a 
much bigger technical difference from 
previously existing equipment than the 
Brute, which is after all only a larger 
carbon arc, the Compact Source equip- 



ment was accepted with much less re- 
sistance. Now, and thanks certainly in 
part to the Journal, there is a much livelier 
interest in technical developments." 

Mr. Jarratt's letter prompted a few 
moments research which revealed the 
following thirteen members with addresses 
in Italy. 

Baume, Alessio, Manager, 16mm, Metro- 

Goldwyn-Mayer, Italy. Mail: Via Camil- 

luccia 71, Roma, Italy. (A, 1947) 
Carrara, Enrico, Vice-President, Cetra Records, 

Corso Pesihiera 10, Torino, Italy. (A, 1949) 
Cambi, Enzo, Consulting Engineer, Cinecitta 

Studios; Lecturer, National Research Council 

(Italy) and Leghorn Naval Academy. Mail: 

Via Giovanni Antonelli 3, Rome, Italy. (A, 

1950) 
Corradi, Amerigo, Tecnostampa, Via Al- 

balonga 38, Rome, Italy. (A, 1950) 
Dalle Rose, Demetrio D., Manager, Western 

Electric Company of Italy, Inc. Mail: Via 

Oglio 9, Rome, Italy. (A, 1946) 
De Renzis, Francesco, Manager, Westrex Co. 

(Italy), Piazza Lovatelli 1, Rome, Italy. 

(A, 1945) 
Innamorati, Libero, Dr. Ing., Centro Speri- 

mentace Cinemato-Grafia. Mail: Via Sa- 

trico 43, Rome, Italy. (A, 1936) 
Jarratt, C. V., Manager, Mole-Richardson 

(Italia), Via Dell'Arco Di Travertine, No. 57, 

Rome, Italy. (A, 1949) 

Marzari, Antonio, Cameraman, Shorts Producer 

and Director, Veneziana Cortometraggi, S. 

Marco 557, Venice, Italy. (A, 1947) 
Monteleoni, Giulio Cesare, Ispettore Tecnico, 

Soc. Ferrania. Mail: Via Crispi 10, Rome, 

Italy. (A, 1948) 
Portalupi, Piero, Director of Photography in 

Motion Picture Production, Lux Film. 

Mail: Viale Bruno Buozzi 83 int F, Rome, 

Italy. (M, 1952) 
Robecchi, Franco, Sound Engineer, Titanus. 

Mail: Piazzale Metronio 1, Rome, Italy. 

(A, 1948) 
Trentino, Victor, Motion Picture Sound 

Engineer, 2 Via Ipponi, Rome, Italy. (A, 

1945) 
Zambuto, Mauro, Technical Director, Scalera 

Films. Mail: Italian Films Export, 1501 

Broadway, New York 36, N.Y. (M, 1952) 



359 



Obituary 




Nathan Levinson died on October 18 at 
his home in Hollywood. He was 64. He 
was head of Warner Brothers sound de- 
partment and well known for his work 
in the early days of sound motion pictures. 
He was credited, with the late Samuel L. 
Warner, with responsibility for the first 
sound film projection which was the 
musical score for Don Juan exhibited in 
New York in August 1926. Voice re- 
production followed in 1927 with the 
release by Warner Brothers' Vitaphone 
Corp. of Al Jolson's The Jazz Singer. 

Born in New York City he was early 
at work as a Western Union messenger. 
After learning telegraphy "on his own," 
Nathan Levinson became a civilian radio 
engineer with Marconi and for the Navy. 
World War I found him a Signal Corps 
Major in command of the Fort Monmouth, 



N.J., Laboratories. In the early twenties 
he was a commercial engineer in the radio 
broadcast field for the Western Electric 
Co. on the Pacific Coast and in 1925 he 
was managing director of San Francisco's 
radio station KPO. A year later he was 
Warner Brothers' sound director and 
western division manager of Vitaphone 
Corp. 

Col. Levinson was a Fellow of this 
Society and most recently served as a 
member of the Theater Television Com- 
mittee. He was awarded the Society's 
Samuel L. Warner Memorial Medal in 
1948 "for his outstanding work in the 
field of motion picture sound recording, 
the intercutting of variable-area and 
variable-density sound tracks, the com- 
mercial use of control track for extending 
volume range, and the use of the first 
sound-proof camera blimps." 

He was interested and instrumental in 
a variety of developments. For instance, 
the use of 16mm motion pictures with 
high-speed development, while not an 
original idea with Col. Levinson, was, 
under his guidance, commercialized for 
recording race-track events. During 
World War II the Navy asked Warner 
Brothers to take over the manufacture of a 
special combat camera and responsibility 
for it was added to Col. Levinson's direc- 
tion of Warner Brothers' sound depart- 
ment. He was a Warner Brothers' repre- 
sentative on the Research Council for the 
past twenty years. In 1941, Col. Levinson 
was given a special award by the Academy 
of Motion Picture Arts and Sciences for 
"outstanding service to the industry and 
to the Army." The next year he received 
the Academy Award for the best sound 
recording, that of Yankee Doodle Dandy. 



SMPTE Lapel Pins 



The Society will have available for mailing after September 15, 1952, its gold and blue 
enamel lapel pin, with a screw back. The pin is a ^-in. reproduction of the Society 
symbol the film, sprocket and television tube which appears on the Journal cover. 
The price of the pin is $4.00, including Federal Tax; in New York City, add 3% 
sales tax. 



360 



New Members 



The following members have been added to the Society's rolls since those last published. The 
designations of grades are the same as those used in the 1952 MEMBERSHIP DIRECTORY. 



Honorary (H) 



Fellow (F) 



Active (M) 



Associate (A) 



Student (S) 



Appleby, Fredericka, New York University. 

Mail: 810 Broadway, Newark, N.J. (S) 
Bell, Charles L., Supervisor of Production 

(East Coast), The Jam Handy Organization, 

1775 Broadway, Rm. 407, New York 19, 

N.Y. (A) 
Birdno, George M., TV Engineer, National 

Broadcasting Co. Mail: 11028 Moorpark 

St., North Hollywood, Calif. (A) 
Bowman, Lester H., Director of Technical 

Operations, CBS-KNX-KNXT, Columbia 

Broadcasting System, Inc., 6121 Sunset Blvd., 

Hollywood 28, Calif. (M) 
Brooke, Ned R., Film Director, WSAZ-TV, 

West Virginia Bldg., Huntington, W. Va. 

(A) 
Brunswick, Lawrence F., Optical Engineer, 

Colorvision, Inc. Mail: 11190 Valley Spring 

PL, North Hollywood, Calif. (M) 
Burton, John W., Motion Picture Photographer, 

Engineer, U.S. Navy, llth Division, Naval 

Air Station, Anacostia 20, D.C. (A) 
Butler, Elliott H., City College, Film Inst. 

Mail: 470 Audubon Ave., New York 33, 

N.Y. (S) 
Cannella, Ben R., Cameraman, Picture House, 

Inc. Mail: c/o Reta Jensen, Mountain, 

Wis. (A) 
Challacombe, Jack A., Foreman, Sensitometric 

Control Dept., Cinecolor Corp., 2800 W. 

Olive, Burbank, Calif. (A) 
Chullasapya, Brig. Gen. Dawee, Royal Thai 

Air Force, Bangkok, Thailand. (M) 
Cochran, Lee W., Director, Bureau of Audio- 
Visual Instruction, State University of Iowa, 

Iowa City, Iowa. (M) 
Connor, Roland E., Equipment Engineer, 

Eastman Kodak Co. Mail: 16 Lilac Dr., 

Rochester, N.Y. (M) 

Cotlov, Nelson, Projectionist, South City Drive- 
in; Film Editor, Capital Film Exchange. 

Mail: 819 Parmley Ave., Yeadon, Pa. (A) 
Craig, Stephen R., Motion Picture Sound 

Engineer, Great Commission Films, Inc. 

Mail: 3455 Meier St., Venice, Calif. (A) 
de Forest, Allan F., Manager, Special Services, 

Peerless Film Processing Corp. Mail: 11 

Bank St., New York, N.Y. (A) 
Embree, Lee R., Motion Picture Photographer, 

U.S. Air Force. Mail: 265 E. Montecito 

Ave., Sierra Madre, Calif. (A) 
Fernandez, R., Carlos, Sound and Theater 
Engineer, J. Glottmann S.A. Mail: Carrera 
19, #47-23, Bogota, Colombia. (M) 



Foy, Walter L., Chemist, E. I. du Pont de 

Nemours & Co. Mail: 78 Van Liew Ave., 

Milltown, N.J. (M) 
Grunwald, Robert, President, Harwald Co., 

Inc., 1261 Chicago Ave., Evanston, 111. (A) 
Hann, William G., Film Technician, Cinecolor 

Corp. Mail: 11626 Chandler Blvd., North 

Hollywood, Calif. (A) 
Harris, Franklin S., Jr., Physicist, Department 

of Physics, University of Utah, Salt Lake 

City 1, Utah. (M) 
Hauser, Willard H., Chief Engineer, WBL- 

TV, Westinghouse Radio Stations, Inc., 1170 

Soldiers Field Rd., Lexington, Mass. (M) 
Howell, Joseph E., Chief Engineer, WDSC. 

Mail: 604 Carthage Rd., Lumberton, N.C. 

(A) 
Hubbard, Ray A., Art Director, KPIX. Mail: 

74 Alta Vista, Mill Valley, Calif. (M) 
Izquierdo, Mike, Sound Engineer, Cines 

Alcazar S.A. (International Amusement Co.). 

Mail: 7539 Taxco Rd., El Paso, Tex. (A) 
Jackson, Robert M., Animation Photographer, 

The Calvin Co. Mail: 4117 Mercier St., 

Kansas City 2, Mo. (A) 
Jackson, William J., Chief Engineer, KEYL, 

San Antonio Television Co., Transit Tower, 

San Antonio, Tex. (M) 
Jewell, James, Television Engineer, Motion 

Picture Cameraman, WWJ-TV. Mail: 

26191 Allen Rd., Trenton, Mich. (M) 
Jost, Hans Joachim, Albrechtstrasse, 78, Berlin- 

Steglitz, Germany. (M) 
Kaak, Henry W., Jr.. Assistant Technical 

Adviser, Camera Dept., Technicolor Motion 

Picture Corp. Mail: 7745 Agnes Ave., North 

Hollywood, Calif. (A) 
Kelly, Michael, Motion Picture Cameraman, 

Northrop Aircraft Co. Mail: 6109 Vic- 
toria Ave., Los Angeles 43, Calif. (M) 
Klein, Max R., Director, Army Film Library 

Services, U.S. Army (Civ. Service). Mail: 

1387 Linden Ave., Highland Park, 111. (M) 
Kraus, Robert W., Apprentice, Motion Picture 

Laboratory Technician, Precision Film 

Laboratories. Mail: 2006 Benson Ave., 

Brooklyn, 14, N.Y. (A) 

Kuriyama, Tetsuzo, Managing Director, Nip- 
pon Onkyo Seiki Co. (Japan Sound Equip- 
ment). Mail: c/o R. A. Haines, FEC Mo- 
tion Picture Div., Special Services Section, 
GHQ, Far East Command, APO 500, c/o 
P.M., San Francisco, Calif. (A) 

361 



Laeser, Phillip B., Television and Radio Engi- 
neer, The Journal Co., WTMJ-TV, 720 E. 
Capitol Dr., Milwaukee, Wis. (M) 

Lapins, Theodore, Engineer, H. de Lanauze 
Cinema Distribution & Service. Mail: Isle 
Perrot, Terrace, Quebec, Canada. (A) 

Lewis, Earl W., Radio-Television Engineer, 
WTVJ. Mail: 795 Harbor Dr., Key 
Biscayne, Miami 49, Fla. (M) 

Lewis, J. Kenneth, Recording Engineer, U.S. 
Navy Dept., Bureau of Ships. Mail: 9209 
48 Ave., College Park, Md. (A) 

Lorenc, Richard M., Electronics Text Develop- 
ment Draftsman, De Forest's Training, Inc. 
Mail: 6925 W. Highland Ave., Chicago 31, 
111. (A) 

Lotz, H. Walter, Factory Superintendent, 
Motiograph, Inc., 4431 W. Lake St., Chicago 
24, 111. (M) 

Love, Nathan, Superintendent Technician, 
Federal Engineering Co. Mail: 376 E. 
Eighth St., Brooklyn 18, N.Y. (A) 

Mejid, Kerim, Motion Picture Cameraman, 
Ministry of Education (Iraq). Mail: Audio- 
Visual Center, 121 College PL, Syracuse, 
N.Y. (A) 

Metzger, William H., Motion Picture Tech- 
nician, Ansco, Div. Gen'l Aniline & Film 
Corp., 405 Lexington Ave., New York, N.Y. 
(A) 

Obata, Toshikazu, Director, Dentsu Motion 
Picture Co. Mail: 104 Mukoyama-Cho, 
Nerima-Ku, Tokyo, Japan. (A) 

Oliver, Francis A., Sound Engineer, American 
Broadcasting Co. Mail: 129 S. Manhattan 
PL, Los Angeles 4, Calif. (M) 

Palenzuela, Carlos V., Sound Engineer, Westrex 
Corp. (Asia). Mail: 418 Sta. Mesa St., 
Manila, Philippines. (A) 

Petersen, Ernest L., Engineering Coordinator, 
Electronics Lab., Northrop Aircraft, Inc. 
Mail: 5205 Calderwood St., Long Beach 4, 
Calif. (A) 

Ramos, Augusto B., Technical Department 
Manager, Philips Portuguesa S.A.R.L. Mail: 
Rua do Telhal, 71-1 -E., Lisbon, Portugal. 
(A) 

Ratcher, Mohammed E., Ill E. 26 St., New 
York 10, N.Y. (A) 

Roberts, Warren S., High-Speed Motion Pic- 
ture Photographer, Sandia Corp. Mail: 
2442 La Vetz Dr., N.E., Albuquerque, N.M. 
(A) 

Schock, William R., Television Engineer, KEYL, 
San Antonio Television Co. Mail: 302 
Freiling Dr., San Antonio 1A, Tex. (A) 

Schuller, Edgar A., Motion Picture Sound Re- 
cording, U.S. Army Signal Corps. Mail: 
30-32 50 St., Woodside, L.I., N.Y. (A) 

Schutz, George, Editor, Quigley Publishing Co., 
RKO Bldg., Rockefeller Center, New York 
20, N.Y. (M) 

362 



Selzer, Robert H., University of California at 
Los Angeles. Mail: 112 N. Highland Ave., 
Los Angeles 36, Calif. (S) 

Sessions, Stanley H., Sound Technician, U.S. 
Navy Electronics Laboratory. Mail: 1886 
Maiden St., San Diego 9, Calif. (A) 

Sombor, Harry, Chief Engineer, Sound Dept., 
Studio Films, Inc. Mail: 1498 Addison 
Rd., Cleveland, Ohio. (M) 

Speed, Richard L., TV Technician, KPIX. 
Mail: 14 Ricardo La., Mill Valley, Calif. 
(A) 

Stainton, Walter H., Cornell University, 
Goldwin Smith Hall, Ithaca, N.Y. (A) 

Stevenson, Paul J., 2231 N. 12 St., Phoenix, 
Ariz. (S) 

Swanell, Lt. Edward F., Motion Picture Officer, 
Film Editor, U.S. Air Force, 1st Photographic 
Sqdn., AP&CS, 200 King St., Alexandria, 
Va. (M) 

Vittum, Paul W., Chemist, Research Super- 
visor, Eastman Kodak Co., Kodak Park 
Works, Rochester 4, N.Y. (M) 

Warndorf, Lt. Col. J. P., Chief, Tech. Photo 
Service Br., Support Div., Wright Air De- 
velopment Center. Mail: 3817 Merrimac 
Ave., Dayton 5, Ohio. (M) 

Watkins, James E., Engineer, Philips Labora- 
tories, Inc., 100 E. 42 St., New York 17, 
N.Y. (M) 

Yoshisaka, Kiyoji, Managing Director, Tokyo 
Theatre Supply Co., Ltd. Mail: c/o R. A. 
Haines, FEC Motion Picture Div., Special 
Services Section, GHQ, Far East Com- 
mand, APO 500, c/o P.M., San Francisco, 
Calif. (A) 

Youngman, John E., Print Foreman, Telefilms, 
Inc. Mail: 4220 McFarlane Ave., Burbank, 
Calif. (A) 

CHANGES IN GRADE 

Arnold, John, (M) to (F) 
Blake, E. E., (M) to (F) 
Cooke, Norman C., (S) to (A) 
Dupy, Olin L., (M) to (F) 
Freund, Karl, (M) to (F) 
Gregory, John R., (S) to (A) 
Gretener, Edgar, (M) to (F) 
Hanson, W. T., Jr., (M) to (F) 
Heppberger, C. E., (M) to (F) 
Hood, Henry J., (M) to (F) 
Ireland, R. Paul, (A) to (M) 
Jensen, A. G., (M) to (F) 
Landsberg, Klaus, (M) to (F) 
Lawrence, C. Richmond, (S) to (A) 
Perkins, Carleton S., (A) to (M) 
Reichard, E. H., (M) to (F) 
Robertson, A. C., (M) to (F) 
Schlanger, Ben, (M) to (F) 
Stott, John G., (M) to (F) 
Templin, E. W., (M) to (F) 
Thulin, Einar, Jr., (S) to (A) 



Position Wanted 



TV Producer-Director: Now Chief of Production in Army's first mobile TV system; 
military experience in writing-directing high-speed, low-cost instructional productions; 
formerly TV producer-director, KRON-TV San Francisco, five shows weekly; will be 
separated from service Nov. 1952; desire connection in educational TV, preferably em- 
ploying kinescope techniques ; married ; prefer West Coast, but willing to travel ; resume, 
script samples, pictures of work on request; 1st Lt. Robert Lownsbery, SigC Mbl TV 
Sys, c/o Sig Photo Center, 35-11 35th Ave., Long Island City 1, N.Y. 



Journals Available and Wanted 

Available 

Upon a reasonable offer to Alfred S. Norbury, 3526 Harrison St., Kansas City 3, Mo. : 

Vol. 44 (Jan.-June 1945) Vol. 50 (Jan.-June 1948) 

Vol. 45 (July-Dec. 1945) Vol. 51 (July-Dec. 1948) 

Vol. 47 (July-Dec. 1946) Vol. 52 (Jan.-June 1949) 

Vol. 48 (Jan.-June 1947) Vol. 56 (Jan.-June 1951) 

Vol. 49 (July-Dec. 1947) Vol. 57 (July-Dec. 1951) 

A set of Journals from January 1945 through 1951 at $15.00 plus packing and carrying 
costs from Richard W. Maedler, 32-52 46 St., Long Island City 3, N.Y. 

Complete set, in excellent condition, from January 1930 to date, plus one issue of Sep- 
tember 1928 from Don Canady, 5125 Myerdale Drive, R.R. 15, Cincinnati 36, Ohio. 

5 years (1947-51) in perfect condition plus the indexes for 1936-45 and 1946-50 and 
including the 1949 High-Speed Photography, upon any reasonable offer to Vic Gretz- 
inger, 3547 Suter St., Oakland 19, Calif. 

I Transactions Nos. 11, 14, 20, 21, 23, 25, 27, 28 and 38; and 22 years of the Journal (1930- 
1951) except for Jan., Feb., Mar. and Apr. of 1934, Jan. and Apr. of 1948, and Feb. 1950; 
also these extra single copies Nov. 1930; Jan., Feb., July and Nov. 1931 ; June 1932; 
Mar. and Apr. 1933; Dec. 1934; Jan. and May 1935; Oct. 1938; July and Dec. 1940; 
Oct. 1948 and Jan. 1950, upon any reasonable offer made to Paul J. Larsen, Assistant to 
the President, Borg- Warner Corp., 310 So. Michigan Ave., Chicago 4, 111. 

Wanted 

Transactions 1, 6 and 7. Contact Mrs. Dorothy Gelatt, Henry M. Lester, 101 Park Ave., 
New York 17, N.Y. 

High-Speed Photography, Volume 1, reprint or original Journal, March 1949, Part II, by 
John H. Waddell, Wollensak Optical Co., 850 Hudson Ave., Rochester 21, N.Y. 



SMPTE Officers and Committees: The roster of Society Officers and the 
Committee Chairmen and Members were published in the April Journal. 



363 



New Products 



Further information about these items can be obtained direct from the addresses given. 
As in the case of technical papers, the Society is not responsible for manufacturers' state- 
ments, and publication of these items does not constitute endorsement of the products. 




Aluminized mirrors specifically designed 
for Schlieren observation and photography 
are now available from J. A. Maurer, Inc., 



Photographic Instrumentation Div., 37-01 
31st St., Long Island City 1, N.Y. The 
Schlieren technique is being widely applied 
to such studies as air and gas flow, aero- 
dynamics, ballistics, and combustion, per- 
mitting visualization and qualitative and 
quantitative analysis. These mirrors, 
manufactured by Optical Works Limited 
of London, England, are available in a 
number of standard sizes from 4 in. to 
18 in. in diameter. Both spherical and 
plane mirrors are included in this series, 
with the spherical mirrors available in 
various focal lengths. These mirrors are 
manufactured to the highest practical 
optical precision and are mounted in 
precise mechanical mounts, permitting 
coarse and fine adjustment about the 
vertical and horizontal axes. Detachable 
metal covers are provided to protect the 
mirrors when not in use. 



Meetings 



American Institute of Electrical Engineers (Symposium on The Science of Music and 
Its Reproduction 1st Lecture), Nov. 7, Engineering Societies Bldg., New York, 

Acoustical Society of America, Nov. 13-15, Balboa Park, San Diego, Calif. 

American Standards Association, Annual Meeting, Nov. 19, Waldorf-Astoria, New York, 

Society of Motion Picture and Television Engineers, Central Section Meeting (in con- 
junction with I.R.E.), Nov. 21, Western Society of Engineers, Chicago, 111. 
American Physical Society, Nov. 28-29, Washington University, St. Louis, Mo. 
Society of Motion Picture and Television Engineers, Central Section Meeting (in con- 
junction with Society of Photographic Engineers), Dec. 3, Bell & Howell Co., Chicago, 

American Institute of Chemical Engineers, Annual Meeting, Dec. 7-10, Cleveland, Ohio 
American Institute of Electrical Engineers (Symposium on The Science of Music and Its 

Reproduction 2d Lecture), Dec. 11, Engineering Societies Bldg., New York, N.Y. 
American Institute of Electrical Engineers (Symposium on the Science of Music and Its 

Reproduction 3d Lecture), Jan. 15, Engineering Societies Bldg., New York, N.Y. 
Institute of Radio Engineers Conference and Electronics Show, 5th Annual Southwestern 

Conference and Show, Feb. 5-7, San Antonio, Texas 
American Institute of Electrical Engineers (Symposium on the Science of Music and Its 

Reproduction 4th Lecture), Feb. 20, Engineering Societies Bldg., New York, N.Y. 

364 



The Economics of 
High-Speed Photography 



By A. C. KELLER 



The economics of the use of high-speed photography in research and de- 
velopment work are discussed. High-speed photography is a relatively new 
tool for engineers which can be used to measure mechanical or electrical 
effects or both at the same time. Examples are given which illustrate the 
savings in engineering manpower as well as in materials, devices and systems. 



I 



T is A PLEASURE to accept the invitation 
of your Chairman to discuss some eco- 
nomic aspects of high-speed photog- 
raphy. Bell Telephone Laboratories, 
of which I am a member, is, as you know, 
a research and development organiza- 
tion and, for this reason, I will cover the 
uses and the value of high-speed photog- 
raphy in this area and will take my 
illustrations from the communications 
field. 

In addressing your Society, of which 
I have been a member for many years, 
I would first like to have you observe 
that it is a society of engineers. I would 
next like you to remember what the char- 
acteristics of an engineer are, particularly 
in contrast to those of the scientist, 
physicist, mathematician, etc. As you 



Presented on October 8, 1952, as the key- 
note speech for the International Sym- 
posium on High-Speed Photography, at 
the Society's Convention at Washington, 
D.C., by A. C. Keller, Bell Telephone 
Laboratories, Inc., 463 West St., New 
York 14, N.Y. 



know, the engineer is indeed interested, 
and must be trained and informed in, 
scientific matters but he has an additional 
responsibility which is in his thoughts 
and actions at all times. This added 
characteristic of the engineer is his con- 
stant concern with the economic value 
of his activities. He always wants to 
know, and must know, whether his proj- 
ects are sound economically. 

In order for the engineer to determine 
the economic value of his work, he must 
have suitable "tools." The tools which 
an engineer uses are of many different 
kinds but none are more important than 
those which are used for measurement 
purposes. He must be able to measure 
many different things in many different 
ways in order to determine the relative 
economics of competing solutions of his 
problems. 

Almost sixty years ago, Lord Kelvin 
discussed the importance of measure- 
ments as follows: "When you can meas- 
ure what you are speaking about, and 
express it in numbers, you know some- 
thing about it; but when you cannot 



November 1952 Journal of the SMPTE Vol. 59 



365 



measure it, when you cannot express 
it in numbers, your knowledge is of a 
meager and unsatisfactory kind; it 
may be the beginning of knowledge, 
but you have scarcely, in your thoughts, 
advanced to the stage of science, what- 
ever the matter may be." This obser- 
vation is probably more important today 
than it was sixty years ago, because our 
apparatus and systems have become more 
and more complex and operate faster 
and faster. 

One of the most important of our rela- 
tively new measuring tools is high-speed 
photography. The use of high-speed 
photography in research and develop- 
ment work leading to new devices and 
new systems and in understanding older 
devices, is becoming increasingly im- 
portant. In our own organization we 
have established a regular service for 
the use of engineers, which is readily 
available, in the form of a variety of 
good equipment and skilled people to 
operate the equipment. 

As measurements are taken of ap- 
paratus or systems we frequently change 
our ideas of how and why devices act as 
they do. I can think of no other tool 
available to the engineer which has 
caused him to change his view of things 
as much as high-speed photography. 
Intuition is a valuable human trait 
but it may easily lead us astray in engi- 
neering matters. It has been said that 
our troubles are not always due to facts 
we do not know but frequently to those 
things that we are sure are true but which 
are in reality untrue. This applies 
particularly to those things which operate 
so fast that they cannot be seen or judged 
by the naked eye. High-speed photog- 
raphy extends our limited human 
powers of observation. It not only 
expands time so that we can readily see 
what happens in extremely short periods 
of time but it also makes possible the 
quantitative measurement of these ef- 
fects. 

High-speed photography itself is a 
broad field of activity and has been 



covered in many excellent papers which 
have appeared in the Journal of this 
Society. However, for the application 
to research and development work, it is 
important to know that high-speed 
photography is capable of expanding 
time for mechanical or electrical effects, 
or for both at the same time. It can 
be used to study fast complex mechanical 
motions and it can also be used to study 
cathode-ray oscilloscope traces of high 
speed. The ability to do these things 
quantitatively has an important eco- 
nomic value. 

The economic value of the use of 
high-speed photography comes about in 
two major ways: 

1 . As a saving in manhours of engineer- 
ing effort by doing a job with fewer 
men, or more likely by doing more 
jobs with the same men; and 

2. As savings in materials, devices or 
systems either by avoiding failures 
in service, by extending the useful 
life of these items or by making faster 
operation possible so that less equip- 
ment may be used to perform the 
required operations. 

To illustrate these savings, some 
specific examples can be cited taken 
from the experiences at Bell Telephone 
Laboratories in research and develop- 
ment activities. 

A good illustration of the savings in 
engineering manpower is the case of 
the development engineer working on a 
new and complex mechanism. With- 
out high-speed photography, it might be 
necessary to build a series of mechanisms 
and to test all of them for performance 
and life, a very expensive proposition 
both in material and in engineering 
manhours. From the experience gained 
with such a large variety of designs, 
it would then be possible to select one 
particular design for application. In 
contrast, the more modern practice 
of using high-speed photography en- 
ables the engineer, sometimes from a 
single model or parts of a model, to 
determine by measurement whether 



366 



November 1952 Journal of the SMPTE Vol. 59 



there are serious shortcomings in the 
newly designed mechanism and what 
the nature of the difficulties is. In 
this way modifications can be made to 
solve problems that may not even be 
known to exist without the help of high- 
speed photography. These methods 
have been used with outstanding success 
in many of our research and develop- 
ment projects, particularly those as- 
sociated with the complex electro- 
mechanical mechanisms which are used 
in telephone central office apparatus. 

A good example of the savings in 
materials, devices or systems which 
result from the use of high-speed photog- 
raphy is one that is present in many 
mechanisms, namely, that of cam actua- 
tion where continuous contact between 
the cam and its follower must be had 
for quiet operation, longest life and 
highest operating speed. Another good 
example is the telephone relay used in 
switching systems. Each of these relays 
has an armature operated by an elec- 
tromagnet. A common problem with 
relays is that of armature rebound when 
a relay is released. The armature may 
bounce one or more times and set up 
other undesirable vibrations in the struc- 
ture. In order to avoid false contact 
operation, it is necessary to wait until 
the effects are over before again allow- 
ing the associated circuits to use the 
relay. By the use of high-speed photog- 
raphy, it has been possible to redesign 
relay structures to minimize these vibra- 
tory effects and the time for them to be 
reduced to a neglibible value. Ac- 
cordingly, the relay can be used by its 
associated circuit more frequently in a 
given length of time. In many cases 
this results in fewer relays in a system to 
provide necessary operating functions. 

From these illustrations it can be said 
that high-speed photography has made 
it possible to produce economies in 
materials, devices or systems by: 
1. Extending the life, with corresponding 
savings in the cost and the materials 
of replacement units, and 



2. Using fewer units to perform the 
needed functions because higher oper- 
ating speeds are possible without un- 
due wear. 

In order to illustrate the variety of 
uses of high-speed photography in the 
research and development area of the 
communications field, a short motion 
picture has been prepared. The film 
has been assembled to indicate the wide 
variety of uses of high-speed photog- 
raphy in our work. After the showing 
of the film, I will attempt to summarize 
the overall economic value of high-speed 
photography in the work at Bell Tele- 
phone Laboratories. 

(Examples were shown in a motion 
picture as follows: 

1. stepping switch for dial systems, 

2. new wire spring relay for dial 
systems, 

3. crossbar switch for dial systems, 

4. mercury contact switch, 

5. automatic trouble recorder, 

6. cam action in automatic message 
accounting equipment, and 

7. pushbutton telephone set.) 

Let us examine the economic value of 
some of the uses of high-speed photog- 
raphy in the telephone apparatus field. 
As you know, the Bell System designs, 
manufactures and uses telephone ap- 
paratus and equipment in large quanti- 
ties to provide much of the nation with 
telephone service. For example, one 
of the scenes in the motion picture film 
showed a study of the step-by-step switch 
used widely in certain types of central 
office dial systems. These switches fol- 
low the dial pulses and perform other 
essential operations in establishing a con- 
nection between telephone subscribers. 
Last year the Bell System manufactured 
more than 600,000 switches of this type. 
It is obvious that savings of even a small 
amount on each of this large number of 
switches would result in a substantial 
sum of money. In the same way, general 
purpose relays are used widely in tele- 
phone switching systems, and in some 
of the modern crossbar systems about 



A. C. Keller: Economics of High-Speed Photography 



367 



five of these are used for each telephone 
subscriber, so that the total number 
produced each year is of the order 
of five million units. Here again, small 
savings, either in the cost of the relay, 
its maintenance or in a reduction of the 
operating time of the relay, have a high 
economic value because a large number 
of them are produced and used each year. 

Another view of the value of high- 
speed photography in Bell System re- 
search and development work can be 
taken from the fact that about 700 to 
800 100-ft reels of high-speed motion 
picture film are taken each year. Most 
of these are carefully studied, frequently 
by a group of engineers. From these 
studies, conclusions are reached which 
result in new and better understandings 
of the devices and frequently design 
changes or new designs are the result. 
Faster processing service of the film 
would be helpful in expediting develop- 
ment work. 

The exact dollar value of the engi- 
neering manhours and materials which 



have been saved by the use of high-speed 
photography is difficult to evaluate but 
it is obviously very large in important 
research and development activities. 
On one particular project of a device 
made in large quantities for telephone 
use, the project engineer estimated that 
savings of several hundred thousand 
dollars a year had resulted. Other proj- 
ects have saved much less and some have 
shown even larger savings. 

In closing, I would like to say that 
there are many other economic advan- 
tages in the use of high-speed photog- 
raphy in maintenance problems, training 
problems, etc., which I have not touched 
upon in outlining the engineering value of 
this tool in research and development 
work. Our daily use of high-speed 
photography, leads us to expect an ex- 
panding application of this new and im- 
portant engineering tool and as a result 
will make better use of that most pre- 
cious commodity engineering man- 
power. 



368 



November 1952 Journal of the SMPTE Vol. 59 



Transient Pressure Recording with a High- 
Speed Interferometer Camera 



By WILLARD E. BUCK 



This paper describes a transient-pressure recording camera with a full scale 
pressure range (by changing diaphragms) of 3 psi to 50,000 psi, and an ac- 
curacy of one-half per cent of full scale for any range. Its stability and hys- 
teresis are such that a single static calibration suffices for years of dynamic 
measurements, and its frequency response varies from 10,000 cycle/sec to 
100,000 cycle/sec, depending on the pressure range of the diaphragm used. 
The paper includes records of interesting applications. 



G 



IONVENTIONAL PRESSURE gauges which 
have high frequency responses are built 
as follows: A pressure-sensitive device 
with the required natural frequency 
(usually a diaphragm or a form of 
Bourdon tube which has a minute dis- 
placement or rotation proportional to 
pressure applied) is the heart of the 
instrument. This small rotation or dis- 
placement is converted into an electrical 
response by an electromechanical trans- 
ducer of the designer's choice, usually 
either a variable condenser or variable 
reluctance device. The small electrical 
impulse thus obtained is amplified and 
recorded without losing the charac- 
teristics of the original signal. 

For frequency responses above about 
2000 cycle/sec, the most convenient 
presentation is on a cathode-ray screen. 
However, if these fleeting signals are to 



Presented on October 10, 1952, at the 
Society's Convention at Washington, 
D. C., by Willard E. Buck, University of 
California Los Alamos Scientific Labora- 
tory, P. O. Box 1663, Los Alamos, N.M. 



be studied, they must be recorded on 
photographic film; and further, if the 
event lasts longer than a very small 
fraction of a second a continuous moving 
film camera is usually required. 

It is obvious that recording the move- 
ment of a diaphragm directly on the 
photographic film is highly desirable if 
the system is sufficiently sensitive and has 
the required frequency response. Such 
a system exists in the familiar form of 
interference fringes which can be re- 
corded directly with a moving film 
camera. 

The unique properties which make 
this system an ideal amplifier are worth 
further discussion. The amplification 
factor, defined as the ratio of distance 
moved by the center of the diaphragm 
to the corresponding change in fringe 
diameter, is 14,620 for a fringe pattern 
using the 5461 A line of mercury and 
having a distance between light maxima 
of 2 mm. The frequency response of 
such an amplifier is approximately half 
the frequency of the light used. In 
this example it would be approximately 



November 1952 Journal of the SMPTE Vol. 59 



369 




QUAKTZ PLATE 



Fig. 1. Schematic of optical system used on interferometer gauge. 



2.7 X 10 14 cycle/sec. The gain of this 
amplifier is as constant as the wavelength 
of light. This, of course, is as good as 
any quantity we know of and is actually 
used as the fundamental standard of 
length measurement. 

With such a satisfactory amplifier the 
characteristics of a pressure measuring 
device depend entirely on the me- 
chanics of the diaphragm and the re- 
cording system used. 

A photographic and optical system 
designed to use such an amplifier was 
first described in October 1948, 1 - 2 but 
is briefly described here again to clarify 
the remainder of this paper for those 
who are not familiar with the inter- 
ferometer gauge. 

Optical System 

In Fig. 1, a steel diaphragm is re- 
ceiving a transient pressure as repre- 
sented by the hammer blow. The 
diaphragm deflects slightly in response 
to the pressure, and it is this slight de- 
flection that we wish to record on the 
moving film. To do this a quartz 
backing plate, with one face ground and 
polished spherically concave on a large 
radius, is placed next to the flat side of 
the diaphragm. The outer edges of 
the plate are ground and polished flat 



to make a highly stable reference with 
respect to the steel diaphragm. 

The spherical cavity in the quartz 
is coated with a half-reflecting film of 
aluminum so that when the assembly is 
viewed in monochromatic light a set 
of sharply defined interference fringes, 
or Newton's rings, is formed. If the 
monochromatic light is admitted through 
a glass prism as shown in the diagram, 
however, only a narrow strip of this set 
of rings is formed. The rings then ap- 
pear as short sections of arcs and may 
be photographed on a moving film as 
distinct parallel lines. Any movement 
of the diaphragm, however, causes a 
change in the air space between the 
quartz plate and the steel, which makes 
an amplified movement at the sections 
of arc and a corresponding change in the 
lines recorded on the moving film. 

In practice, the quartz backing piece 
is ground to produce approximately 50 
fringes. Since a deflection of about 
one-tenth of a fringe can be measured 
on the film, the displacement of the dia- 
phragm can be measured to about one 
part in 500. 

As long as the deflection of the dia- 
phragm stays well below the elastic 
limit of the steel or quartz used, it is 
strictly proportional to the pressure 
applied. The number of fringes from 



370 



November 1952 Journal of the SMPTE Vol. 59 




Fig. 2. Cutaway of first self-contained model of interferometer gauge. 



the outer ring, which is in contact with 
the diaphragm, to the center of the 
diaphragm is directly proportional to the 
distance from the center of the dia- 
phragm to the quartz backing plate; 
therefore, the number of fringes counted 
on a photographic film is directly pro- 
portional to the pressure applied. This 
linear relationship is, of course, a highly 
desirable feature for ease of calibration 
and interpretation of records. 

Camera Details 

The camera proper is of the familiar 
continuous moving film variety, but 
the special features of various models 
which have been developed should be 
mentioned. 

The general scheme for film transport 
is the same on all models, and consists 
of a high-speed motor directly coupled 
to the take-up spool. The speed of the 



motor is controlled by a governor which 
is mounted on an idler drum driven 
by the friction of the film being pulled 
over it. Thus the motor speed is 
varied to give a constant film speed as 
the take-up reel increases in size. On 
most models the film speed can be con- 
trolled from 10 to 80 ft/sec. The sup- 
ply spool has an adjustable drag to keep 
tension on the film which supplies driving 
power for the governor and to keep the 
film in the image plane. One model 
which was intended for short runs has a 
magnetic fluid brake 3 on the take-up reel 
which is supplied with power as soon 
as the driving motor circuit is broken. 
This camera will make as many as ten 
runs on a 100-ft spool of film at 80 
ft/sec, and have the major part of each 
run at full speed. 

One model is equipped with a footage 
counter which reveals the amount of 



W. E. Buck: Pressure Recording With Interferometer Camera 



371 



film left in the camera, and has a dial 
which can be set for the required film 
length in the next run. 

Figure 2 is a cutaway drawing of the 
first self-contained interferometer gauge 
ever built. It was designed to measure 
the internal pressure of rocket motors 
in the range of to 2000 psi. To keep 
the hot gases of the rocket motor from 
destroying the diaphragm, the pressure 
is conducted to the diaphragm by a 
short oil line. By choosing the proper 
viscosity of oil and the proper size of 
line, the diaphragm can be critically 
damped. The oil line then acts as a 
low-pass filter so that the frequency re- 
sponse of the system is the frequency 
response of the oil line itself. By keeping 
the line short and making sure there is 
no air in the system, the frequency re- 
sponse can be held above 10,000 cycle/ 
sec. In the lower left corner of Fig. 2 
is a blower fan used to keep the light 
cool. This is necessary because ap- 
proximately 100 w of power must be 
consumed to get a sufficiently bright 
source. Between the two film spools 
is a slotted disc which is driven by a 
synchronous motor and puts timing 
marks on the edge of the film by inter- 
rupting the main light beam. The slots 
in this drum are of varying depths giving 
5, 10 and 20 millisecond marks with 
increased lengths of line in each case 
to assist in analyzing the film. 

In the center of the camera and next 
to the film frame is a holder for a small 
cylindrical lens. This lens is not shown 
in the optical diagram (Fig. 1) as it is 
not an essential component, but it does 
serve to reduce the size of the image of 
the slot on the film, thus increasing the 
frequency response that can be read for 
any given film speed. Mounted with 
its roller on the take-up spool is a micro- 
switch which is operated by the increas- 
ing diameter of the take-up spool. This 
switch interrupts the current to the drive 
motor and applies energy to the brake 
on the supply spool. 



Figure 3 is a picture of a model that 
was intended primarily for measuring 
pressures in blast waves, although it has 
proven to be a versatile camera and has 
been put to many other uses. The plate 
marked "Mounting for Quartz Dia- 
phragm" is mounted flush with the 
surface over which the shock wave 
travels. This may be either the inside 
of the shock tube or the surface of the 
ground, as the experiment requires. 
The main features of this design are its 
ease of construction and its ruggedness. 
It is, of course, designed to stand the 
jars that it will receive when measuring 
shock waves. As in all very high speed 
cameras, there is a problem in keeping 
the end of the film intact as the driving 
motor comes to a stop. If the film is 
allowed to run free, approximately 1 in. 
is snapped off on every revolution, and 
at approximately 10,000 rpm, an ap- 
preciable section of the film can be 
destroyed in a very short time. To 
prevent this loss of record, two pre- 
cautions have been taken. One is the 
microswitch which cuts off the power 
when the reel gets full, and the second 
is the two spring leaves which can be seen 
on either side of the take-up spool. 
These leaves are mounted so that, as 
the spool gets full, the film bears against 
the springs and acts as a brake to bring 
the motor to a stop in a very short 
time. With these two precautionary 
measures in operation the film can be 
used to within a few feet of the end of 
the spool without fear of losing a record. 

Figure 4 shows the latest 16mm camera 
design. It is intended to measure pres- 
sures in free air or anywhere else that 
a small size is important. The camera 
model shown in Figs. 2 and 3 has self- 
contained power supplies and needs 
only to be supplied with 110 v a-c and a 
starting signal. However, this latest 
camera requires an external power 
supply as well as a starting signal. As 
can be seen from the picture, the case 
is extremely rugged and will stand 
pressures of 100-lb shock without being 



372 



November 1952 Journal of the SMPTE Vol. 59 



MOUNTING FOR QUARTZ 

DIAPHRAGM 




MING LIGHT 



CYLINDRSCAL 
LENS 



MICRO SWITCH 



FILM SPOOLS 



Fig. 3. Interior of model designed for blast-pressure measurements. 




Fig. 4. Compact 16mm interferometer gauge. 
W. E. Buck: Pressure Recording With Interferometer Camera 373 




DAMPING FLUID 



Fig. 5. Drawing of quartz diaphragm and damping assembly. 



damaged. The diaphragm assembly 
shown in the extreme left is easily de- 
tachable, and diaphragms varying in 
range from 3 psi to 50,000 psi can be 
quickly substituted. This makes a single 
instrument that can record the pressure 
wave from a hand clap as well as the 
internal pressures of our largest rifles. 

Diaphragm Construction 

For pressures in the range of 3 to 100 
psi it is possible and desirable to use a 
quartz diaphragm instead of the steel 
diaphragm shown in Fig. 1. Figure 5 
is a drawing of this diaphragm assembly. 

Fused quartz is an almost ideal ma- 
terial for a pressure diaphragm. Its 
ratio of Young's modulus to density 
is high, thus allowing a high natural 
frequency for a given pressure range. 
Fused quartz also has one of the smallest 
temperature coefficients known, and 
consequently its calibration is almost 
independent of temperature. The most 
interesting feature of the quartz dia- 
phragm, however, is its ability to be 
optically contacted with another piece 
of fused quartz. This property allows 
us to build a diaphragm and a backing 
plate optically contacted together to form 
a single integral unit. This system is 
so stable that it requires only one careful 
static calibration for the life of the 
instrument. 

To sum up the features of this as- 
sembly, we have the following charac- 
teristics : 



1. High frequency response for a 
given pressure range. 

2. A negligibly small temperature 
coefficient. 

3. A stability that permits a single 
calibration for the life of the gauge. 

4. No detectable hysteresis. 

Damping 

This quartz diaphragm, with almost 
perfect elastic properties, will vibrate 
at its natural frequency for a long time 
when subjected to a shock wave if not 
properly damped. One of the most 
difficult problems in the design of this 
instrument was to find the proper 
damping method for the quartz dia- 
phragm. All sorts of schemes were 
tried, but all systems that gave adequate 
damping loaded a diaphragm so much 
that they reduced its natural frequency 
two or three times. This, of course, was 
highly undesirable, as one of the main 
features of the gauge is its high frequency 
response. Finally, almost by accident, 
it was found that if the direction of 
motion of the damping fluid was at 
right angles to that of the diaphragm, 
the mass of the damper did not add to 
the mass of the diaphragm and hence 
the frequency response was not de- 
stroyed. To accomplish this damping 
it was only necessary to bring a rigid 
metal support close to the front surface 
of the diaphragm in such a way that a 
drop of the proper viscosity fluid could 



374 



November 1952 Journal of the SMPTE Vol. 59 




.- .s .6 

TIME IN MILLISECONDS 

Fig. 6. Enlargement of an original record and method of plotting 
pressure-time curve. 



be placed between the diaphragm and 
the metal support. 

As the diaphragm deflects, the oil 
must flow along the face of the dia- 
phragm to accommodate the change in 
volume between the diaphragm and the 
metal support. Damping is caused by 
the viscosity of the oil. Decreasing the 
clearance between the support and the 
diaphragm will increase the velocity of 
the oil and hence its damping action. 
A 0.040-in. diaphragm with a pressure 
range of to 70 psi is critically damped 
if a 1000-centistoke oil drop is used 
with a clearance of about 0.004 in. 



Figure 5 also shows the diaphragm 
damper and filter unit combination. 
The damping fluid is held in place 
between the metal plate and the dia- 
phragm by its surface tension. After 
several months of field use, diaphragms 
have been inspected, and the oil drops 
have been found to be intact and damp- 
ing properly. 

As these gauges are intended for field 
use of the most exacting kind, it was 
found necessary to put a water and dust 
filter over the diaphragm proper. The 
material used for this filter has the trade 
name "Porex." It is manufactured by 



W. E. Buck: Pressure Recording With Interferometer Camera 



375 



Chorge: 22.62 # Comp B 
Distance 24 ft 
Scale I fringe =! 67PSI 
Shape cylindrical 




Fig. 7. Blast-pressure curve of small charge showing 
three separate shocks arriving at gauge. 



40 








































32 














/ 




\ 


































/ 








\ 
































i 








s 


r 
















5f 


& 










2 












\ 


r 














22840^ 


* 








/ 
















^s 


s 












S 








,/ 


1 




















^ 


-^Q 












A 


? * 


^ 


























*- , 


-o^. 


o- 






I 








































/ 










































; 


> 


i 


\ 


< 




( 


5 


1 


3 


1 


z 


1 


4 


I 


5 







Time in Milliseconds 



Fig. 8. Pressure-time plot of internal pressure developed 
by a typical large-caliber rifle. 



Moraine Products Division of General 
Motors Corp. "Porex" is made of a 
large number of small beads which are 
bonded on their outer edges by heat 
and pressure until the whole unit is 
quite rigid but leaving a fair percentage 
of air passage between the balls. The 
"Porex" after manufacture is dipped 
into hot paraffin and the excess paraffin 
blown out with compressed air. This 
leaves each individual ball coated with 
a very thin layer of paraffin which will 
not be wet with water droplets. A 
"Porex" filter thus treated will not pass 
water even though it is immersed one- 
quarter inch or so. A blast gauge thus 



protected can be left out in the dust 
and rain even though its sensitive 
diaphragm is turned up flush with the 
ground. By keeping the volume of air 
small and the area of the "Porex" disc 
large, the flow time is so rapid that it 
does not measurably decrease the fre- 
quency response of the diaphragm. 

Records 

It is difficult to find a practical record 
that can be displayed on a magazine 
page, as most events of interest are a 
number of milliseconds long and would 
require many feet of paper to present 
them adequately. The record of Fig. 6 



376 



November 1952 Journal of the SMPTE Vol. 59 



was chosen because the whole event 
could be shown on a single sheet of 
paper. This figure not only shows an 
enlargement of the original record, and 
the graph of pressure vs. time obtained 
from it, but also sho